armv7m: Improve "-d mmu" tracing for PMSAv7 MPU

armv7m: Improve "-d mmu" tracing for PMSAv7 MPU

Improve the "-d mmu" tracing for the PMSAv7 MPU translation
process as an aid in debugging guest MPU configurations:
 * fix a missing newline for a guest-error log
 * report the region number with guest-error or unimp
   logs of bad region register values
 * add a log message for the overall result of the lookup
 * print "0x" prefix for hex values

Signed-off-by: Michael Davidsaver <[email protected]>
Reviewed-by: Alistair Francis <[email protected]>
Reviewed-by: Philippe Mathieu-Daudé <[email protected]>
Message-id: 1493122030[email protected]
[PMM: a little tidyup, report region number in all messages
 rather than just one]
Signed-off-by: Peter Maydell <[email protected]>