target-arm: implement SCTLR.B, drop bswap_code

target-arm: implement SCTLR.B, drop bswap_code

bswap_code is a CPU property of sorts ("is the iside endianness the
opposite way round to TARGET_WORDS_BIGENDIAN?") but it is not the
actual CPU state involved here which is SCTLR.B (set for BE32
binaries, clear for BE8).

Replace bswap_code with SCTLR.B, and pass that to arm_ld*_code.
The next patches will make data fetches honor both SCTLR.B and
CPSR.E appropriately.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
[PC changes:
 * rebased on master (Jan 2016)
 * s/TARGET_USER_ONLY/CONFIG_USER_ONLY
 * Use bswap_code() for disas_set_info() instead of raw sctlr_b
]
Signed-off-by: Peter Crosthwaite <crosthwaite.peter@gmail.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>