The Capstone disassembler has its own big-endian fixup.
Doing this twice does not work, of course.  Move our current
fixup from target/arm/cpu.c to disas/arm.c.

This makes read_memory_inner_func unused and can be removed.

Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>