uapi: Use __kernel_long_t in struct timex

x32 adjtimex system call is the same as x86-64 adjtimex system call,
which uses 64-bit integer for long in struct timex. But x32 long is
32 bit.  This patch replaces long in struct timex with __kernel_long_t.

Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
Link: http://lkml.kernel.org/r/1388182464-28428-2-git-send-email-hjl.tools@gmail.com
Signed-off-by: H. Peter Anvin <hpa@zytor.com>