dumpstack: x86: various small unification steps, fix

After "dumpstack: x86: various small unification steps", the
assembler gives the following compile error. The error is in
dumpstack_64.c.

{standard input}: Assembler messages:
{standard input}:720: Error: Incorrect register `%rbx' used with `l' suffix
{standard input}:1340: Error: Incorrect register `%r12' used with `l' suffix

Indeed the suffix in get_bp() was wrong.
Signed-off-by: NAlexander van Heukelum <heukelum@fastmail.fm>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

arch/x86/kernel/dumpstack_64.c

@@ -17,7 +17,7 @@
 #include <asm/stacktrace.h>
 
 #define STACKSLOTS_PER_LINE 4
-#define get_bp(bp) asm("movl %%rbp, %0" : "=r" (bp) :)
+#define get_bp(bp) asm("movq %%rbp, %0" : "=r" (bp) :)
 
 int panic_on_unrecovered_nmi;
 int kstack_depth_to_print = 3 * STACKSLOTS_PER_LINE;