src/include: improve the description of hexstrtobin

Specify how hexstrtobin.c processes the strings of odd length.

Signed-off-by: Anna Karas <aka@semihalf.com>
Change-Id: Ie8cd8fb93d7dab08c5e7f28fc511b6381f5ad13a
Reviewed-on: https://review.coreboot.org/c/coreboot/+/43089
Reviewed-by: Paul Fagerburg <pfagerburg@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/include/lib.h

@@ -40,6 +40,8 @@ void hexdump32(char LEVEL, const void *d, size_t len);
  *
  * Defined in src/lib/hexstrtobin.c
  * Ignores non-hex characters in the string.
+ * Ignores the last hex character if the number of hex characters in the string
+ * is odd.
  * Returns the number of bytes that have been put in the buffer.
  */
 size_t hexstrtobin(const char *str, uint8_t *buf, size_t len);