MAINTAINERS: Switch to @amd.com emails

@xilinx.com is still working but better to switch to new amd.com after
AMD/Xilinx acquisition.

Acked-by: Shubhrajyoti Datta <shubhrajyoti.datta@amd.com>
Acked-by: Radhey Shyam Pandey <radhey.shyam.pandey@amd.com>
Signed-off-by: Michal Simek <michal.simek@amd.com>
Link: https://lore.kernel.org/r/f7773fdd002f89578b9e5262692a563fe7be4123.1684244928.git.michal.simek@amd.com