arm64: dts: ti: k3-am64-mcu: Fix the compatible string in GPIO DT node

Fix the compatible string in mcu domain GPIO device tree node.

Fixes: 01a91e01 ("arm64: dts: ti: k3-am64: Add GPIO DT nodes")
Signed-off-by: Aswath Govindraju <a-govindraju@ti.com>
Reviewed-by: Lokesh Vutla <lokeshvutla@ti.com>
Signed-off-by: Nishanth Menon <nm@ti.com>
Link: https://lore.kernel.org/r/20210423060133.16473-1-a-govindraju@ti.com