src/soc: Remove unused <stdlib.h>

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

Change-Id: I08e1a680de9bfcc7d74e88a15abe9eef327b4961
Signed-off-by: Elyes HAOUAS <ehaouas@noos.fr>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/60617
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Jonathan Zhang <jonzhang@fb.com>

src/soc/amd/picasso/agesa_acpi.c

@@ -18,7 +18,6 @@
 #include <amdblocks/ioapic.h>
 #include <soc/data_fabric.h>
 #include <soc/pci_devs.h>
-#include <stdlib.h>
 #include <arch/mmio.h>
 
 static unsigned long gen_crat_hsa_entry(struct acpi_crat_header *crat, unsigned long current)