intel: agilex: Fix build error

"result of '1 << 31' requires 33 bits to represent, but 'int' only has
32 bits [-Werror=shift-overflow=]"

This is treated as an error since commit 93c690eb ("Enable
-Wshift-overflow=2 to check for undefined shift behavior")

Change-Id: I141827a6711ab7759bfd6357e4ed9c1176da7c7b
Signed-off-by: Ambroise Vincent <ambroise.vincent@arm.com>