arm64: cleanup unused UDBG_* define

The UDBG_UNDEFINED/SYSCALL/BADABORT/SEGV are only used to show
verbose user fault messages in arm, not arm64, drop them.
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

arch/arm64/include/asm/system_misc.h

@@ -56,12 +56,6 @@ extern void (*arm_pm_restart)(enum reboot_mode reboot_mode, const char *cmd);
 	__show_ratelimited;						\
 })
 
-#define UDBG_UNDEFINED	(1 << 0)
-#define UDBG_SYSCALL	(1 << 1)
-#define UDBG_BADABORT	(1 << 2)
-#define UDBG_SEGV	(1 << 3)
-#define UDBG_BUS	(1 << 4)
-
 #endif	/* __ASSEMBLY__ */
 
 #endif	/* __ASM_SYSTEM_MISC_H */