x86: Eliminate result signage problem in asm-x86_64/bitops.h

The return type of __scanbit() doesn't match the return type of
find_{first,next}_bit().  Thus when you construct something like
this:

   boolean ? __scanbit() : find_first_bit()

you get an unsigned long result if "boolean" is true, and a signed
long result if "boolean" is false.

In file included from /home/cel/src/linux/include/linux/mmzone.h:15,
                 from /home/cel/src/linux/include/linux/gfp.h:4,
                 from /home/cel/src/linux/include/linux/slab.h:14,
                 from /home/cel/src/linux/include/linux/percpu.h:5,
                 from
/home/cel/src/linux/include/linux/rcupdate.h:41,
                 from /home/cel/src/linux/include/linux/dcache.h:10,
                 from /home/cel/src/linux/include/linux/fs.h:275,
                 from /home/cel/src/linux/fs/nfs/sysctl.c:9:
/home/cel/src/linux/include/linux/nodemask.h: In function
‘__first_node’:
/home/cel/src/linux/include/linux/nodemask.h:229: warning: signed and
unsigned type in conditional expression
/home/cel/src/linux/include/linux/nodemask.h: In function
‘__next_node’:
/home/cel/src/linux/include/linux/nodemask.h:235: warning: signed and
unsigned type in conditional expression
/home/cel/src/linux/include/linux/nodemask.h: In function
‘__first_unset_node’:
/home/cel/src/linux/include/linux/nodemask.h:253: warning: signed and
unsigned type in conditional expression

[ tglx: arch/x86 adaptation ]

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>