configs: j721e_evm_a72: Fix redundant environment offset

The current environment offset overlaps with the sysfw area and whenever
environment is saved in the redundant slot, it overwrites sysfw.itb. Fix
the offset to prevent this.

Signed-off-by: Faiz Abbas <faiz_abbas@ti.com>
Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>