ENGR00265465 gpu:Add global value for minimum 3D clock export

ENGR00265465 gpu:Add global value for minimum 3D clock export

Add global value gpu3DMinClock so that minimum 3D clock can be change by user.
When gpu min clock is too low, it may cause IPU starvation issue in certain case.
Use echo x > /sys/module/galcore/parameters/gpu3DMinClock to change it.

Signed-off-by: Loren Huang <b02279@freescale.com>
Acked-by: Lily Zhang