ice: Add helper function ice_is_generic_mac

E800 series devices have a couple of quirks:
1. Sideband control queues are not supported
2. The registers that the driver needs to program for the "Precision
   Time Protocol (PTP)" feature are different for E800 series devices
   compared to other devices supported by this driver.

Both these require conditional logic based on the underlying device we
are dealing with.

The function ice_is_sbq_supported added by commit 8f5ee3c4


("ice: add support for sideband messages") addresses (1).
The same function can be used to address (2) as well
but this just looks weird readability wise in cases that have nothing
to do with sideband control queues:

	if (ice_is_sbq_supported(hw))
		/* program register A */
	else
		/* program register B */

For these cases, the function ice_is_generic_mac introduced by this
patch communicates the idea/intention better. Also rework
ice_is_sbq_supported to use this new function.
As side-band queue is supported for E825C devices, it's mac_type is
considered as generic mac_type.

Co-developed-by: Anirudh Venkataramanan <anirudh.venkataramanan@intel.com>
Signed-off-by: Anirudh Venkataramanan <anirudh.venkataramanan@intel.com>
Signed-off-by: Grzegorz Nitka <grzegorz.nitka@intel.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Tested-by: Pucha Himasekhar Reddy <himasekharx.reddy.pucha@intel.com> (A Contingent worker at Intel)
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>