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 <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Joe MacDonald <joe.macdonald@windriver.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Acked-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/mm/subpage-prot.c

@@ -95,7 +95,8 @@ static void subpage_prot_clear(unsigned long addr, unsigned long len)
 	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);
@@ -144,7 +145,8 @@ long sys_subpage_prot(unsigned long addr, unsigned long len, u32 __user *map)
 	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;