linux-user: arm: handle CPSR.E correctly in strex emulation

linux-user: arm: handle CPSR.E correctly in strex emulation

Now that CPSR.E is set correctly, prepare for when setend will be able
to change it; bswap data in and out of strex manually by comparing
SCTLR.B, CPSR.E and TARGET_WORDS_BIGENDIAN (we do not have the luxury
of using TCGMemOps).

Signed-off-by: Paolo Bonzini <[email protected]>
[ PC changes:
  * Moved SCTLR/CPSR logic to arm_cpu_data_is_big_endian
]
Signed-off-by: Peter Crosthwaite <[email protected]>
Reviewed-by: Peter Maydell <[email protected]>
Signed-off-by: Peter Maydell <[email protected]>