arm: print instructions pointed to by pc

If an exception occurs in a loaded image and the relocation offset is
unknown, it is helful to know the instructions pointed to by the
program counter. This patch adds the missing output.

A possible output is:
    Code: e1c560d0 e12fff1e e120077b e12fff1e (e7f7defb)

The parentheses indicate the instruction causing the exception.

The output can be disassembled using the decodecode script provided
by the Linux kernel project.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>