power: reset: at91-reset: Optimize at91_reset()

This patch adds a small optimization to the low-level at91_reset()
function, which includes:
- Removes the extra branch, since the following store operations
  already have proper condition checks.
- Removes the definition of the clobber register r4, since it is
  no longer used in the code.

Fixes: fcd0532 ("power: reset: at91-reset: make at91sam9g45_restart() generic")
Signed-off-by: Alexander Shiyan <eagle.alexander923@gmail.com>
Reviewed-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20250307053809.20245-1-eagle.alexander923@gmail.com
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

Author: shcgit

drivers/power/reset/at91-reset.c

@@ -129,12 +129,11 @@ static int at91_reset(struct notifier_block *this, unsigned long mode,
 		"	str	%4, [%0, %6]\n\t"
 		/* Disable SDRAM1 accesses */
 		"1:	tst	%1, #0\n\t"
-		"	beq	2f\n\t"
 		"	strne	%3, [%1, #" __stringify(AT91_DDRSDRC_RTR) "]\n\t"
 		/* Power down SDRAM1 */
 		"	strne	%4, [%1, %6]\n\t"
 		/* Reset CPU */
-		"2:	str	%5, [%2, #" __stringify(AT91_RSTC_CR) "]\n\t"
+		"	str	%5, [%2, #" __stringify(AT91_RSTC_CR) "]\n\t"
 
 		"	b	.\n\t"
 		:
@@ -145,7 +144,7 @@ static int at91_reset(struct notifier_block *this, unsigned long mode,
 		  "r" cpu_to_le32(AT91_DDRSDRC_LPCB_POWER_DOWN),
 		  "r" (reset->data->reset_args),
 		  "r" (reset->ramc_lpr)
-		: "r4");
+	);
 
 	return NOTIFY_DONE;
 }