scripts/gdb: account for changes in module data structure

Commit 7523e4dc

 ("module: use a structure to encapsulate layout.")
factored out the module_layout structure.  Adjust the symbol loader and
the lsmod command to this.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Reviewed-by: Kieran Bingham <kieran.bingham@linaro.org>
Tested-by: Kieran Bingham <kieran.bingham@linaro.org> (qemu-{ARM,x86})
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Jason Wessel <jason.wessel@windriver.com>
Cc: <stable@vger.kernel.org>	[4.4+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>