gdbstub: Change gdb_get_reg_cb and gdb_set_reg_cb

gdbstub: Change gdb_get_reg_cb and gdb_set_reg_cb

Align the parameters of gdb_get_reg_cb and gdb_set_reg_cb with the
gdb_read_register and gdb_write_register members of CPUClass to allow
to unify the logic to access registers of the core and coprocessors
in the future.

Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20231213-gdb-v17-6-777047380591@daynix.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20240227144335.1196131-11-alex.bennee@linaro.org>