pcdp: use early_ioremap/early_iounmap to access pcdp table

pcdp: use early_ioremap/early_iounmap to access pcdp table

efi_setup_pcdp_console() is called during boot to parse the HCDP/PCDP EFI
system table and setup an early console for printk output.  The routine
uses ioremap/iounmap to setup access to the HCDP/PCDP table information.
The call to ioremap is happening early in the boot process which leads to
a panic on x86_64 systems:

    0xffffffff815ffbd4 panic+0x01ca
    0xffffffff810535ec do_exit+0x043c
    0xffffffff81603847 oops_end+0x00a7
    0xffffffff81042859 no_context+0x0119
    0xffffffff81042a68 __bad_area_nosemaphore+0x0138
    0xffffffff81042b5e bad_area_nosemaphore+0x000e
    0xffffffff81606411 do_page_fault+0x0321
    0xffffffff81602cb0 page_fault+0x0020
    0xffffffff81045fc1 reserve_memtype+0x02a1
    0xffffffff810430a3 __ioremap_caller+0x0123
    0xffffffff81043402 ioremap_nocache+0x0012
    0xffffffff81d53e70 efi_setup_pcdp_console+0x002b
    0xffffffff81d1fcc5 setup_arch+0x03a9
    0xffffffff81d19b44 start_kernel+0x00d4
    0xffffffff81d19341 x86_64_start_reservations+0x012c
    0xffffffff81d19449 x86_64_start_kernel+0x00fe

This patch replaces the calls to ioremap/iounmap in
efi_setup_pcdp_console() with calls to early_ioremap/early_iounmap which
can be called during early boot.

This patch was tested on an x86_64 prototype system which uses the
HCDP/PCDP table for early console setup.

Signed-off-by: Greg Pearson <greg.pearson@hp.com>
Acked-by: Khalid Aziz <khalid.aziz@hp.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>