net: systemport: Move IO macros to header file

Move the BCM_SYSPORT_IO_MACRO() definition and its use to bcmsysport.h
where it is more appropriate and where static inline helpers are
acceptable. While at it, make sure that the macro 'offset' argument does
not trigger a checkpatch warning due to possible argument re-use.

Suggested-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: Florian Fainelli <florian.fainelli@broadcom.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20241021174935.57658-3-florian.fainelli@broadcom.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>