debug: use assert's when approperiate

error was returned instead of using assert.

Signed-off-by: Øyvind Harboe <oyvind.harboe@zylin.com>

src/target/arm_jtag.h

@@ -45,8 +45,7 @@ static inline int arm_jtag_set_instr(struct arm_jtag *jtag_info,
 	/* inline most common code path */
 	struct jtag_tap *tap;
 	tap = jtag_info->tap;
-	if (tap == NULL)
-		return ERROR_FAIL;
+	assert (tap != NULL);
 
 	if (buf_get_u32(tap->cur_instr, 0, tap->ir_length) != new_instr)
 	{

src/target/xscale.c

@@ -160,8 +160,7 @@ static int xscale_verify_pointer(struct command_context *cmd_ctx,
 
 static int xscale_jtag_set_instr(struct jtag_tap *tap, uint32_t new_instr, tap_state_t end_state)
 {
-	if (tap == NULL)
-		return ERROR_FAIL;
+	assert (tap != NULL);
 
 	if (buf_get_u32(tap->cur_instr, 0, tap->ir_length) != new_instr)
 	{