drivers/spi/spiconsole.c: Remove unuseful 'return' in void function

Change-Id: Ie5c83f16146517d0aa37cd1975de725f57323094
Signed-off-by: Elyes HAOUAS <ehaouas@noos.fr>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/61484
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Martin Roth <martinroth@google.com>

src/drivers/spi/spiconsole.c

@@ -9,7 +9,6 @@ static struct spi_slave slave;
 void spiconsole_init(void) {
 	spi_init();
 	spi_setup_slave(0, 0, &slave);
-	return;
 }
 
 /*
@@ -49,6 +48,4 @@ void spiconsole_tx_byte(unsigned char c) {
 
 		msg.header.msg_length = 0;
 	}
-
-	return;
 }