arm: dts: agilex: Increase reserved memory size to 32MB

The reserved space is extended to 32MB in Linux kernel because
additional space is needed for authorization execution of JIC/RBF file.
U-Boot required to align with Linux.

Signed-off-by: Dinesh Maniyam <dinesh.maniyam@intel.com>
Reviewed-by: Tien Fong Chee <tien.fong.chee@intel.com>