src/drivers/i2c/gpiomux: Remove unused <stdlib.h>

Found using:
diff <(git grep -l '#include <stdlib.h>' -- src/) <(git grep -l 'memalign(\|malloc(\|calloc(\|free(' -- src/)

Change-Id: Id3bd3d8a2d3609a13ecbc4eab14ba745e6365cab
Signed-off-by: Elyes HAOUAS <ehaouas@noos.fr>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/60619
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Felix Held <felix-coreboot@felixheld.de>

src/drivers/i2c/gpiomux/bus/bus.c

@@ -5,8 +5,8 @@
 #include <console/console.h>
 #include <device/device.h>
 #include <device/path.h>
-#include <stdlib.h>
 #include <string.h>
+
 #include "chip.h"
 
 static const char *i2c_gpiomux_bus_acpi_name(const struct device *dev)

src/drivers/i2c/gpiomux/mux/mux.c

@@ -5,8 +5,8 @@
 #include <console/console.h>
 #include <device/device.h>
 #include <device/path.h>
-#include <stdlib.h>
 #include <string.h>
+
 #include "chip.h"
 
 static const char *i2c_gpiomux_mux_acpi_name(const struct device *dev)