plat: ti: k3: common: bl31_setup: Use BL31_SIZE instead of computing
plat: ti: k3: common: bl31_setup: Use BL31_SIZE instead of computing

We compute BL31_END - BL31_START on the fly, which is basically
BL31_SIZE. Lets just use the BL31_SIZE directly so that we dont
complicate PIE relocations when actual address is +ve and -ve offsets
relative to link address.

Signed-off-by: Nishanth Menon <50c3c575ce2bb12c45e20736ce59e86fe81915b4@ti.com>
Change-Id: I5e14906381d2d059163800d39798eb39c42da4ec

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