feat(neoverse-rd): add MHUv3 channels on third gen multichip platforms

Add MHUv3 doorbell channel information to scmi_channel_plat_info_t for
third generation of multichip Neoverse reference design platforms.

Signed-off-by: Rohit Mathew <Rohit.Mathew@arm.com>
Signed-off-by: Vivek Gautam <vivek.gautam@arm.com>
Change-Id: Ie4ebf47a10f2f6e33c7ecfc8008e30bacc62bf3d
1 file changed