Revert "Initial support for Broadcom VideoCore / BCM21553"

This reverts commit 3c71468dc3e2e608865bfe5913ecbb6fc7c11f51.

Change-Id: Ie821b4cb74c82b06890b295a95491aa6064134d3
bionic: allow direct TLS access on ARMv6-VFP arch

When ARCH_ARM_HAVE_TLS_REGISTER is true, build libc and linker
in arm mode (to workaround the missing MCR/MRC registers in thumb
mode).

Change-Id: I5148a037da2e80c91798c742638b1d81d9f1352a