Makefile: Add rules for carray sources in lib/sbi

Add back the missing rules needed to build carray files in lib/sbi. This
allows future usage of carray in lib/sbi.

Fixes: de80e933

 ("Makefile: Compile lib/utils sources separately for each platform")
Signed-off-by: Vivian Wang <dramforever@live.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Anup Patel <anup@brainfault.org>