Avoids an error from the assembler for CONFIG_THUMB2 kernels:

clang-15: error: hardware TLS register is not supported for the thumbv4t
sub-architecture

This flag only makes sense to pass to the compiler, not the assembler.

Perhaps CFLAGS_ABI can be renamed to CPPFLAGS_ABI to reflect that they
will be passed to both the compiler and assembler for sources that
require pre-processing.
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>