target-arm: Don't define any MMU_MODE*_SUFFIXes

target-arm: Don't define any MMU_MODE*_SUFFIXes

target-arm doesn't use any of the MMU-mode specific cpu ldst
accessor functions. Suppress their generation by not defining
any of the MMU_MODE*_SUFFIX macros. ("user" and "kernel" are
too simplistic as descriptions of indexes 0 and 1 anyway.)

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Greg Bellows <greg.bellows@linaro.org>
Reviewed-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>