asm-generic: Use __BITS_PER_LONG in statfs.h

commit f5c2347ee20a8d6964d6a6b1ad04f200f8d4dfa7 upstream.

<asm-generic/statfs.h> is exported to userspace, so using
BITS_PER_LONG is invalid.  We need to use __BITS_PER_LONG instead.

This is kernel bugzilla 43165.

Reported-by: H.J. Lu <hjl.tools@gmail.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Link: http://lkml.kernel.org/r/1335465916-16965-1-git-send-email-hpa@linux.intel.com
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>