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: fcd0532fac2a ("power: reset: at91-reset: make at91sam9g45_restart() generic")
Signed-off-by: Alexander Shiyan <[e-mail]>
Reviewed-by: Alexandre Belloni <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Sebastian Reichel <[e-mail]>

drivers/power/reset/at91-reset.c

···
 		"	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"
 		:
···
 		  "r" cpu_to_le32(AT91_DDRSDRC_LPCB_POWER_DOWN),
 		  "r" (reset->data->reset_args),
 		  "r" (reset->ramc_lpr)
-		: "r4");
+	);
 
 	return NOTIFY_DONE;
 }