staging: vchiq_core: Move remote_event_signal() vchiq_core

staging: vchiq_core: Move remote_event_signal() vchiq_core

The function remote_event_signal() is declared in vchiq_core.h while
defined in vchiq_arm.c and used only in vchiq_core.c. Move the
definition to vchiq_core.c as it is only used in this file.

Also convert it to static and drop the function signature from
vchiq_core.h header. BELL2 doorbell macro is also moved from vchiq_arm
to vchiq_core as part of this change.

No functional changes intended in this patch.

Signed-off-by: Umang Jain <umang.jain@ideasonboard.com>
Reviewed-by: Dan Carpenter <dan.carpenter@linaro.org>
Link: https://lore.kernel.org/r/20240919142130.1331495-2-umang.jain@ideasonboard.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>