writeback: fix ppc compile warnings on do_div(long long, unsigned long)
writeback: fix ppc compile warnings on do_div(long long, unsigned long)

Fix powerpc compile warnings

mm/page-writeback.c: In function 'bdi_position_ratio':
mm/page-writeback.c:622:3: warning: comparison of distinct pointer types lacks a cast [enabled by default]
page-writeback.c:635:4: warning: comparison of distinct pointer types lacks a cast [enabled by default]

Also fix gcc "uninitialized var" warnings.

Reported-by: Stephen Rothwell <4bf0fb350827ce8d86875e76c923a478597c3cef@canb.auug.org.au>
Signed-off-by: Wu Fengguang <24f7fe9d205c8a9f6ade0c2894e14303ca16087f@intel.com>

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