SPM: FPU: Use the correct defines to access ICB

The symbol ICB is defined in CMSIS_6 only for devices which
are based on Armv8.1-M architecture, while to access the
Implementation Control Block register in other targets the
define to use is SCnSCB. This is because the SCnSCB_Type is
replaced by the ICB_Type definitions only for Armv8.1-M
headers.

Signed-off-by: Antonio de Angelis <antonio.deangelis@arm.com>
Change-Id: I165fa01bbf7cebb484955f024b4c12ae0c35663c
1 file changed