tracing: gfp: Remove duplication of recording GFP flags

tracing: gfp: Remove duplication of recording GFP flags

The gfp_flags when recorded in the trace require being converted from
their numbers to values. Various macros are used to help facilitate this,
but there's two sets of macros that need to keep track of the same GFP
flags to stay in sync.

Commit 60295b944ff68 ("tracing: gfp: Fix the GFP enum values shown for
user space tracing tools") added a TRACE_GFP_FLAGS macro that holds the
enum ___GFP_*_BIT defined bits, and creates the TRACE_DEFINE_ENUM()
wrapper around them.

The __def_gfpflag_names() macro creates the mapping of various flags or
multiple flags to give them human readable names via the __print_flags()
tracing helper macro.

As the TRACE_GFP_FLAGS is a subset of the __def_gfpflags_names(), it can
be used to cover the individual bit names, by redefining the internal
macro TRACE_GFP_EM():

  #undef TRACE_GFP_EM
  #define TRACE_GFP_EM(a) gfpflag_string(__GFP_##a),

This will remove the bits that are duplicate between the two macros. If a
new bit is created, only the TRACE_GFP_FLAGS needs to be updated and that
will also update the __def_gfpflags_names() macro.

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Veronika Molnarova <vmolnaro@redhat.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/20250225135611.1942b65c@gandalf.local.home
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>