x86, x32: Use __kernel_long_t for __statfs_word

x32 statfs system call is the same as x86-64 statfs system call, which
uses 64-bit integer for __statfs_word.  This patch defines __statfs_word
as __kernel_long_t instead of long.

Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
Link: http://lkml.kernel.org/r/CAMe9rOrcppHvC5g8U9n7D%2BpxVGdu1G598pge3Erfw7Pr-iEpAQ@mail.gmail.com
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>