soc/intel/apollolake: Fix issues detected by checkpatch

Fix the following errors and warnings detected by checkpatch.pl:

ERROR: switch and case should be at the same indent
ERROR: do not use assignment in if condition
WARNING: Statements terminations use 1 semicolon
WARNING: unnecessary whitespace before a quoted newline
WARNING: else is not generally useful after a break or return

TEST=Build for reef

Change-Id: I5486936dbf19b066c76179d929660affa1da5f16
Signed-off-by: Lee Leahy <leroy.p.leahy@intel.com>
Reviewed-on: https://review.coreboot.org/18727
Tested-by: build bot (Jenkins)
Reviewed-by: Martin Roth <martinroth@google.com>

src/soc/intel/apollolake/acpi.c

@@ -58,7 +58,7 @@ static int acpi_sci_irq(void)
 static unsigned long acpi_madt_irq_overrides(unsigned long current)
 {
 	int sci = acpi_sci_irq();
-	uint16_t flags = MP_IRQ_TRIGGER_LEVEL | MP_IRQ_POLARITY_LOW;;
+	uint16_t flags = MP_IRQ_TRIGGER_LEVEL | MP_IRQ_POLARITY_LOW;
 
 	/* INT_SRC_OVR */
 	current += acpi_create_madt_irqoverride((void *)current, 0, 0, 2, 0);