clean up type-casting twice.  "size_t" is typedef as "unsigned long" in
64-bit system, and "unsigned int" in 32-bit system, and the intermediate
cast to 'long' is pointless.
Signed-off-by: NFigo.zhang <figo1802@gmail.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>