gfs2: Introduce glock_{type,number,sbd} helpers

gfs2: Introduce glock_{type,number,sbd} helpers

Introduce glock_type(), glock_number(), and glock_sbd() helpers for
accessing a glock's type, number, and super block pointer more easily.

Created with Coccinelle using the following semantic patch:

@@ struct gfs2_glock *gl; @@
- gl->gl_name.ln_type
+ glock_type(gl)

@@ struct gfs2_glock *gl; @@
- gl->gl_name.ln_number
+ glock_number(gl)

@@ struct gfs2_glock *gl; @@
- gl->gl_name.ln_sbd
+ glock_sbd(gl)

glock_sbd() is a macro because it is used with const as well as
non-const struct gfs2_glock * arguments.

Instances in macro definitions, particularly in tracepoint definitions,
replaced by hand.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>