firmware: xilinx: Switch Michal Simek's email to new one

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

Signed-off-by: Michal Simek <michal.simek@amd.com>
Link: https://lore.kernel.org/r/36d119221aa12369c601cd37160306aeb84fc973.1684244767.git.michal.simek@amd.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>