ENGR00225735-1 PU anatop: PU regulator can be disabled/enabled by drivers

ENGR00225735-1 PU anatop: PU regulator can be disabled/enabled by drivers

Before, PU regulator only be turned off in DSM, which means it kept on in
system normal mode even GPU/VPU driver didn't run. To decrease power number,
PU regulator can be disabled/enabled by GPU/VPU driver, and the voltage value
is tracked by VDDARM which change in cpufreq driver.The patch including:
1.implement PU regulator enable/disable interface in anatop regulator driver
2.remove gpu_power_down and gpu_power_up in system suspend/resume flow.
3.skip change pu regulator set if it has been disabled.

Note: There is three power supply on  VDDPU:
a).Use internal anatop PU regulator, VDDDPU_IN is fixed. In this case,VDDPU_CAP
can be turned off or dynamic change by internal anatop(track with VDDSOCi_CAP).
In other words, it use "cpu_vddvpu" regulator as PU regulator,not only in GPU/
VPU driver, but also in cpufreq driver.Sabresd,Sololite EVK is in this case if
disable CONFIG_MX6_INTER_LDO_BYPASS.

b).Use external pmic regulator as PU regulator, it means in LDO bypass way
(CONFIG_MX6_INTER_LDO_BYPASS).But VDDPU_IN is connected with VDDSOC_IN. Because
VDDSOC can't be turned off for ever, and VDDPU track with VDDSOC always, we
remove  "pu_id", so that cpufreq driver will never touch it.But GPU/VPU driver
will turn off/on VDDPU_CAP by disabling/enabling "cpu_vddvpu".In this case,
although VDDPU_IN is supplied by external pmic in hardware level, but we can't
turn off external pmic directly, because it connect with VDDSOC_IN.So only we
can do is turn off VDDPU_CAP by internal anatop regulator("cpu_vddvpu").Sabresd
,Sololite EVK is in this case if enable CONFIG_MX6_INTER_LDO_BYPASS.

c).Use external pmic regulator as PU regulator, it means in LDO bypass way
(CONFIG_MX6_INTER_LDO_BYPASS). And VDDPU_IN is in dependent with VDDSOC_IN(
whether short in VDDPU_IN with VDDPU_CAP directly or not).In this case,the only
thing we need to do is that add the right external vddpu regulator name to
"pu_id" in their boad file, and nothing else.
Just like below (arch/arm/mach-mx6/board-mx6sl_evk.c):

static struct mxc_dvfs_platform_data mx6sl_evk_dvfscore_data = {
	.reg_id			= "VDDCORE",
	.soc_id			= "VDDSOC",
	*******************************************************************
	.pu_id	= "what you used VDDPU_IN regulator name from external pmic"
	*******************************************************************
	.reg_id			= "cpu_vddgp",
	.soc_id			= "cpu_vddsoc",
	.pu_id			= "cpu_vddvpu",
	......

Signed-off-by: Robin Gong <b38343@freescale.com>