soc: xilinx: update maintainer of event manager driver

Added Michal as a maintainer of event manager driver as Abhyuday is no
longer active.

Signed-off-by: Jay Buddhabhatti <jay.buddhabhatti@amd.com>
Signed-off-by: Michal Simek <michal.simek@amd.com>
Link: https://lore.kernel.org/r/0171170571802fe96b49cefbca9c87f3c1c9eee6.1702919377.git.michal.simek@amd.com