unicore32: abort when entering "x 0" on the monitor

Starting Qemu with "qemu-system-unicore32 -M puv3,accel=qtest -S -nographic"
and entering "x 0 " at the monitor prompt leads to abort():

  $ ./unicore32-softmmu/qemu-system-unicore32 -M puv3,accel=qtest -S -nographic
  QEMU 2.9.90 monitor - type 'help' for more information
  (qemu) x 0
  qemu: fatal: uc32_cpu_get_phys_page_debug not supported yet

  R00=00000000 R01=00000000 R02=00000000 R03=00000000
  R04=00000000 R05=00000000 R06=00000000 R07=00000000
  R08=00000000 R09=00000000 R10=00000000 R11=00000000
  R12=00000000 R13=00000000 R14=00000000 R15=00000000
  R16=00000000 R17=00000000 R18=00000000 R19=00000000
  R20=00000000 R21=00000000 R22=00000000 R23=00000000
  R24=00000000 R25=00000000 R26=00000000 R27=00000000
  R28=00000000 R29=00000000 R30=00000000 R31=03000000
  PSR=40000013 -Z-- PRIV
  Aborted (core dumped)

This happens because uc32_cpu_get_phys_page_debug() is not implemented
yet, this is a temporary workaround to avoid the crash.

Signed-off-by: Eduardo Otubo <otubo@redhat.com>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
