[ARM] nommu: we need the TLS register emulation for nommu mode

Since there can be no fixed location for the TLS value with nommu
systems, we must provide TLS register emulation in order to support
TLS binaries on CPUs without the thread register.

Part of a patch from Hyok S. Choi, and cleaned up by rmk.

Signed-off-by: Hyok S. Choi <hyok.choi@samsung.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>