net: rswitch: Replace enum rswitch_reg with plain macros

net: rswitch: Replace enum rswitch_reg with plain macros

Replace enum rswitch_reg with plain #define REGISTER OFFSET macros.
The enum rswitch_reg was not referenced anywhere, so there was no
benefit of keeping it around. Include register block labels. Turn
all register offsets into lowercase hex values. No functional change.

Rename EATDQDC to EATDQDCR, GWTRC to GWTRCR, GWDCC to GWDCCR, FWPC0
to FWPC, FWPBFC to FWPBFCR, FWPBFCSDC to FWPBFCSDCR because there
are both register names which used to be part of this enum and also
macros with the same name, each used for slightly different purpose.
Make sure there is no collission.

Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>