netfs: Generate enums from trace symbol mapping lists

netfs: Generate enums from trace symbol mapping lists

netfs has a number of lists of symbols for use in tracing, listed in an
enum and then listed again in a symbol->string mapping for use with
__print_symbolic().  This is, however, redundant.

Instead, use the symbol->string mapping list to also generate the enum
where the enum is in the same file.

Changes
=======
ver #3)
 - #undef EM and E_ at the end of the trace file[1].

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Jeff Layton <jlayton@redhat.com>
cc: linux-cachefs@redhat.com

Link: https://lore.kernel.org/r/c2f4b3dc107b106e04c48f54945a12715cccfdf3.camel@redhat.com/
Link: https://lore.kernel.org/r/164622980839.3564931.5673300162465266909.stgit@warthog.procyon.org.uk/
Link: https://lore.kernel.org/r/164678192454.1200972.4428834328108580460.stgit@warthog.procyon.org.uk/
Link: https://lore.kernel.org/r/CALF+zOkB38_MB5QwNUtqTU4WjMaLUJ5+Piwsn3pMxkO3d4J7Kg@mail.gmail.com/
Link: https://lore.kernel.org/r/164692890614.2099075.12960653141802151575.stgit@warthog.procyon.org.uk/