Remove cortex-a53 linker workaround for new cpus.

Bug: 78133793

Test: Built target with cortex-a53 and verified that the flag is still
Test: there.
Test: Build target with cortex-a55/cortex-a75 and verified that the flag
Test: is not there.
Test: Built and booted on a taimen, ran bionic unit tests.
Change-Id: Ibd7f497ecf46e5781cd0265463b0782babdf062a