de-duplicate calls to xfs_attr_trace_enter

Every call to xfs_attr_trace_enter() shares the exact same 16 args in the
middle... just send in the context pointer and let the next level down
split it into the ktrace.

Compile tested only.

SGI-PV: 976035
SGI-Modid: xfs-linux-melb:xfs-kern:31200a
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>
Signed-off-by: Niv Sardi <xaiki@sgi.com>
Signed-off-by: Josef 'Jeff' Sipek <jeffpc@josefsipek.net>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>