target/arm/tcg/cpu32.c: swap ATCM and BTCM register names

target/arm/tcg/cpu32.c: swap ATCM and BTCM register names

According to Cortex-R5 r1p2 manual, register with opcode2=0 is
BTCM and with opcode2=1 is ATCM, - exactly the opposite from how
qemu labels them.  Just swap the labels to avoid confusion, -
both registers are implemented as always-zero.

Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20241121171602.3273252-1-mjt@tls.msk.ru
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>