Hotfix: Correct link script section name

ER_EFLASH_DRIVER_RO section name is replaced by ER_CODE_SRAM.
So, the related definitions need to be updated too.

Signed-off-by: Summer Qin <summer.qin@arm.com>
Change-Id: I7f899595bdfe89e6f6bad09c655feb3db22f81ae