powerpc: Fix 8xx build failure
powerpc: Fix 8xx build failure

The 'powerpc ioremap_prot' broke 8xx builds:

include2/asm/pgtable-ppc32.h:555: error: '_PAGE_WRITETHRU' undeclared (first use in this function)
include2/asm/pgtable-ppc32.h:555: error: (Each undeclared identifier is reported only once
include2/asm/pgtable-ppc32.h:555: error: for each function it appears in.)

Signed-off-by: Kumar Gala <383ef5577c6e1178b93f59ec8d0936f76d2a98c4@kernel.crashing.org>
Signed-off-by: Benjamin Herrenschmidt <a7089bb6e7e92505d88aaff006cbdd60cc9120b6@kernel.crashing.org>

KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs