[XFS] Fix xfs_lowbit64
[XFS] Fix xfs_lowbit64

xfs_lowbit64 was broken on 32 bit platforms in a recent cleanup of the xfs
bitops. Fix it back up again.

SGI-PV: 974005
SGI-Modid: xfs-linux-melb:xfs-kern:30202a

Signed-off-by: David Chinner <d2f98f0f27147ca85564d32aa37577d3673e6910@sgi.com>
Signed-off-by: Lachlan McIlroy <f5e96ceb240f4c6b121fe0445b266d7666b5fe0e@sgi.com>

TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs