Kconfig: zynqmp: Move CONFIG_SYS_TEXT_BASE to defconfig

Move CONFIG_SYS_TEXT_BASE of ZynqMP_ep to its
respective defconfig

Signed-off-by: Siva Durga Prasad Paladugu <sivadur@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>