powerpc/mm: Match variable types to API

sys_subpage_prot() takes an unsigned long for 'addr' then does some stuff
with it and the result is stored in a signed int, i, which is eventually
used as the size parameter in a copy_from_user call. Update 'i' to be an
unsigned long as well and since 'nw' is used in a size_t context which,
depending on whether this is 32- or 64-bit may be unsigned int or unsigned
long, switch that to a size_t and always be right.

Finally, since we're in the neighbourhood, make the same changes to
subpage_prot_clear().

Cc: Paul Mackerras <[e-mail]>
Cc: Benjamin Herrenschmidt <[e-mail]>
Signed-off-by: Joe MacDonald <[e-mail]>
Signed-off-by: Paul Gortmaker <[e-mail]>
Acked-by: Paul Mackerras <[e-mail]>
Signed-off-by: Benjamin Herrenschmidt <[e-mail]>

arch/powerpc/mm/subpage-prot.c

···
 	struct mm_struct *mm = current->mm;
 	struct subpage_prot_table *spt = &mm->context.spt;
 	u32 **spm, *spp;
-	int i, nw;
+	unsigned long i;
+	size_t nw;
 	unsigned long next, limit;
 
 	down_write(&mm->mmap_sem);
···
 	struct mm_struct *mm = current->mm;
 	struct subpage_prot_table *spt = &mm->context.spt;
 	u32 **spm, *spp;
-	int i, nw;
+	unsigned long i;
+	size_t nw;
 	unsigned long next, limit;
 	int err;