libxfs: fix byte swapping on constants

libxfs: fix byte swapping on constants

The kernel code uses cpu_to_beXX() on constants in switch()
statements for magic numbers in the btree code. The byte swapping
infratructure isn't hooked up to the proper byte swap macros to make
this work, so fix it and then swap all the generic btree code over
to match the kernel code.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Review-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Rich Johnston <rjohnston@sgi.com>