kcov: fix comparison callback signature

Fix a silly copy-paste bug.  We truncated u32 args to u16.

Link: http://lkml.kernel.org/r/20171207101134.107168-1-dvyukov@google.com
Fixes: ded97d2c2b2c ("kcov: support comparison operands collection")
Signed-off-by: Dmitry Vyukov <dvyukov@google.com>
Cc: syzkaller@googlegroups.com
Cc: Alexander Potapenko <glider@google.com>
Cc: Vegard Nossum <vegard.nossum@oracle.com>
Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kernel/kcov.c

@@ -157,7 +157,7 @@ void notrace __sanitizer_cov_trace_cmp2(u16 arg1, u16 arg2)
 }
 EXPORT_SYMBOL(__sanitizer_cov_trace_cmp2);
 
-void notrace __sanitizer_cov_trace_cmp4(u16 arg1, u16 arg2)
+void notrace __sanitizer_cov_trace_cmp4(u32 arg1, u32 arg2)
 {
 	write_comp_data(KCOV_CMP_SIZE(2), arg1, arg2, _RET_IP_);
 }
@@ -183,7 +183,7 @@ void notrace __sanitizer_cov_trace_const_cmp2(u16 arg1, u16 arg2)
 }
 EXPORT_SYMBOL(__sanitizer_cov_trace_const_cmp2);
 
-void notrace __sanitizer_cov_trace_const_cmp4(u16 arg1, u16 arg2)
+void notrace __sanitizer_cov_trace_const_cmp4(u32 arg1, u32 arg2)
 {
 	write_comp_data(KCOV_CMP_SIZE(2) | KCOV_CMP_CONST, arg1, arg2,
 			_RET_IP_);