arm: socfpga: Enable ASYNC interrupts in Agilex SPL

arm: socfpga: Enable ASYNC interrupts in Agilex SPL

Asynchronous aborts were previously masked at SPL
entry.

To ensure early detection of system errors
such as ECC faults or bus errors, asynchronous aborts
should be explicitly unmasked by clearing the A-bit in
the DAIF register during Agilex SPL initialization.

Signed-off-by: Alif Zakuan Yuslaimi <alif.zakuan.yuslaimi@altera.com>
Reviewed-by: Tien Fong Chee <tien.fong.chee@altera.com>
# Conflicts:
#	arch/arm/mach-socfpga/spl_agilex.c