arm: mach-k3: am62a7_init: Open up FSS_DAT_REG3 firewall

On security enforced (HS-SE) devices ROM firewalls OSPI data region3 that
is present in above 64bit region. Open this up in bootloader to allow
Linux to access OSPI flashes in mmap mode.

Without this kernel will crash when accessing this region due to
firewall violations on HS-SE devices.

Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>