sh: Fix up kgdb-on-NMI branch target.

This was all reworked some time ago, the old debug_enter was ripped
out with everything going through a debug trap jump table instead.
Kill off the debug_enter target and reference kgdb_handle_exception
directly.

Signed-off-by: Paul Mundt <[e-mail]>

arch/sh/kernel/cpu/sh3/ex.S

···
 	.long	exception_error	! illegal_slot_instruction (filled by trap_init) /*1A0*/
 ENTRY(nmi_slot)
 #if defined (CONFIG_KGDB_NMI)
-	.long	debug_enter	/* 1C0 */	! Allow trap to debugger
+	.long	kgdb_handle_exception	/* 1C0 */	! Allow trap to debugger
 #else
 	.long	exception_none	/* 1C0 */	! Not implemented yet
 #endif