plat/arm: tzc_dmc500: Add missing plat_arm.h include
plat/arm: tzc_dmc500: Add missing plat_arm.h include

This omission causes a build error as the definition for
arm_tzc_regions_info_t is needed from plat_arm.h

Change-Id: I26935ee90d3e36ab6a016ff2c4eee4413df3e4e8
Signed-off-by: Nariman Poushin <2f8dfc1642bf854c964b211c0e960f1ed63c75bd@linaro.org>

achingupta/arm-trusted-firmware,achingupta/arm-trusted-firmware