rtc: renesas-rtca3: Disable interrupts only if the RTC is enabled

If the RTC is not enabled and the code attempts to disable the interrupt,
the readb_poll_timeout_atomic() function in the
rtca3_alarm_irq_set_helper() may timeout, leading to probe failures.
This issue is reproducible on some devices because the initial values of
the PIE and AIE bits in the RCR1 register are undefined.

To prevent probe failures in this scenario, disable RTC interrupts only
when the RTC is actually enabled.

Fixes: d4488377609e ("rtc: renesas-rtca3: Add driver for RTCA-3 available on Renesas RZ/G3S SoC")
Signed-off-by: Claudiu Beznea <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Alexandre Belloni <[e-mail]>

drivers/rtc/rtc-renesas-rtca3.c

···
 	 */
 	usleep_range(sleep_us, sleep_us + 10);
 
-	/* Disable all interrupts. */
-	mask = RTCA3_RCR1_AIE | RTCA3_RCR1_CIE | RTCA3_RCR1_PIE;
-	ret = rtca3_alarm_irq_set_helper(priv, mask, 0);
-	if (ret)
-		return ret;
-
 	mask = RTCA3_RCR2_START | RTCA3_RCR2_HR24;
 	val = readb(priv->base + RTCA3_RCR2);
-	/* Nothing to do if already started in 24 hours and calendar count mode. */
-	if ((val & mask) == mask)
-		return 0;
+	/* Only disable the interrupts if already started in 24 hours and calendar count mode. */
+	if ((val & mask) == mask) {
+		/* Disable all interrupts. */
+		mask = RTCA3_RCR1_AIE | RTCA3_RCR1_CIE | RTCA3_RCR1_PIE;
+		return rtca3_alarm_irq_set_helper(priv, mask, 0);
+	}
 
 	/* Reconfigure the RTC in 24 hours and calendar count mode. */
 	mask = RTCA3_RCR2_START | RTCA3_RCR2_CNTMD;