i965: Fix 32 bit build warnings in intel_get_yf_ys_bo_size()

i965: Fix 32 bit build warnings in intel_get_yf_ys_bo_size()

Along with fixing the type of pitch parameter, patch also changes
the types of few local variables and function return type.

Warnings fixed are:
intel_mipmap_tree.c:671:7: warning: passing argument 3 of
'intel_get_yf_ys_bo_size' from incompatible pointer type

intel_mipmap_tree.c:563:1: note: expected 'uint64_t *' but
argument is of type 'long unsigned int *'

Signed-off-by: Anuj Phogat <anuj.phogat@gmail.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>