Fix(extra mem): Fix additonal memory allocation for MPU-based systems #341

Job	Run time
build-arm (fvp-a, GICV2)	1m 35s
build-arm (fvp-a, GICV2, CROSS_COMPILE=clang)	1m 40s
build-arm (fvp-a, GICV3)	1m 35s
build-arm (fvp-a, GICV3, CROSS_COMPILE=clang)	1m 36s
build-arm (fvp-a-aarch32, GICV2)	2m 5s
build-arm (fvp-a-aarch32, GICV2, CROSS_COMPILE=clang)	2m 3s
build-arm (fvp-a-aarch32, GICV3)	1m 35s
build-arm (fvp-a-aarch32, GICV3, CROSS_COMPILE=clang)	1m 40s
build-arm (fvp-r, GICV2)	1m 32s
build-arm (fvp-r, GICV2, CROSS_COMPILE=clang)	2m 7s
build-arm (fvp-r, GICV3)	1m 36s
build-arm (fvp-r, GICV3, CROSS_COMPILE=clang)	2m 4s
build-arm (fvp-r-aarch32, GICV2)	1m 32s
build-arm (fvp-r-aarch32, GICV2, CROSS_COMPILE=clang)	1m 39s
build-arm (fvp-r-aarch32, GICV3)	1m 37s
build-arm (fvp-r-aarch32, GICV3, CROSS_COMPILE=clang)	1m 36s
	27m 32s

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