util/cbfstool: Fix typos

Found by: util/lint/checkpatch.pl --types TYPO_SPELLING --fix-inplace
--strict --terse -f util/cbfstool/*.c

Change-Id: I13a27407bf2bad4b9fadcec8cdbd5889068f13cf
Signed-off-by: Patrick Georgi <pgeorgi@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/38633
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: HAOUAS Elyes <ehaouas@noos.fr>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

util/cbfstool/elfheaders.c

@@ -658,7 +658,7 @@ void elf_init_eheader(Elf64_Ehdr *ehdr, int machine, int nbits, int endian)
 	}
 }
 
-/* Arbitray maximum number of sections. */
+/* Arbitrary maximum number of sections. */
 #define MAX_SECTIONS 16
 struct elf_writer_section {
 	Elf64_Shdr shdr;