ARM: at91: pm: save and restore ACR during PLL disable/enable

Add a new word in assembly to store ACR value during the calls
to at91_plla_disable/at91_plla_enable macros and use it.

Signed-off-by: Nicolas Ferre <nicolas.ferre@microchip.com>
[cristian.birsan@microchip.com: remove ACR_DEFAULT_PLLA loading]
Signed-off-by: Cristian Birsan <cristian.birsan@microchip.com>
Link: https://lore.kernel.org/r/20250827145427.46819-4-nicolas.ferre@microchip.com
Reviewed-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Claudiu Beznea <claudiu.beznea@tuxon.dev>

Author: noglitch

arch/arm/mach-at91/pm_suspend.S

@@ -689,6 +689,10 @@ sr_dis_exit:
 	bic	tmp2, tmp2, #AT91_PMC_PLL_UPDT_ID
 	str	tmp2, [pmc, #AT91_PMC_PLL_UPDT]
 
+	/* save acr */
+	ldr	tmp2, [pmc, #AT91_PMC_PLL_ACR]
+	str	tmp2, .saved_acr
+
 	/* save div. */
 	mov	tmp1, #0
 	ldr	tmp2, [pmc, #AT91_PMC_PLL_CTRL0]
@@ -758,7 +762,7 @@ sr_dis_exit:
 	str	tmp1, [pmc, #AT91_PMC_PLL_UPDT]
 
 	/* step 2. */
-	ldr	tmp1, =AT91_PMC_PLL_ACR_DEFAULT_PLLA
+	ldr	tmp1, .saved_acr
 	str	tmp1, [pmc, #AT91_PMC_PLL_ACR]
 
 	/* step 3. */
@@ -1207,6 +1211,8 @@ ENDPROC(at91_pm_suspend_in_sram)
 #endif
 .saved_mckr:
 	.word 0
+.saved_acr:
+	.word 0
 .saved_pllar:
 	.word 0
 .saved_sam9_lpr: