powerpc/modules: Improve restore_r2() error message

powerpc/modules: Improve restore_r2() error message

BugLink: http://bugs.launchpad.net/bugs/1741992
Print the function address associated with the restore_r2() error to
make it easier to debug the problem.

Also clarify the wording a bit.

Before:

  module_64: patch_foo: Expect noop after relocate, got 3c820000

After:

  module_64: patch_foo: Expected nop after call, got 7c630034 at netdev_has_upper_dev+0x54/0xb0 [patch_foo]

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
[mpe: Change noop to nop, as that's the name of the instruction]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
(cherry picked from commit 1ea61ea23985c0f15c027e4c0ac02224efdfb243)
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>