feat(corstone1000): made changes to accommodate 3MB for optee

These changes are required to accommodate 3MB for OP-TEE and this
is required for SP's part of optee
Added size macro's for better readability of the code
Moved uboot execution memory from CVM to DDR

Change-Id: I16657c6e336fe7c0fffdee1617d10af8a2c76732
Signed-off-by: Vishnu Banavath <vishnu.banavath@arm.com>
Signed-off-by: Arpita S.K <Arpita.S.K@arm.com>