armv7a_mmu: s/LOG_ERROR/LOG_WARNING/ on address translation failure

armv7a_mmu: s/LOG_ERROR/LOG_WARNING/ on address translation failure

When GDB analyses the status of the target it try to guess the
current stack frame and issues few memory read.
E.g. on ARM targets GDB uses R11 value as a potential frame-pointer
and reads at the address pointed by R11.
The address of such memory read is not always valid and can trigger
an address translation failure.

Replace LOG_ERROR with LOG_WARNING in case the virtual address does
not have a hit in TTB; print the virtual address in the warning
message and discriminate the two identical messages with [1]/[2].

Change-Id: I288b8cd26bec2543c4f1c16b7c06dc47d5d843d1
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-on: http://openocd.zylin.com/4602
Tested-by: jenkins
Reviewed-by: Spencer Oliver <spen@spen-soft.co.uk>