arch: arm64: Fix arm64 crash dump output

- x0/x1 register printing is reversed
- The error stack frame struct (z_arch_esf_t) had the SPSR and ELR in
  the wrong position, inconsistent with the order these regs are pushed
  to the stack in z_arm64_svc.  This caused all register printing to be
  skewed by two.
- Verified by writing known values (abcd0000 -> abcd000f) to x0 - x15
  and then forcing a data abort.

Signed-off-by: Luke Starrett <luke.starrett@gmail.com>