firmware: dmi_scan: Use lowercase letters for UUID

RFC 4122 asks for letters a-f in UUID to be lowercase. Follow this
recommendation.

Suggested by Paul Dagnelie at:
https://savannah.nongnu.org/bugs/index.php?53569

Signed-off-by: Jean Delvare <[e-mail]>

drivers/firmware/dmi_scan.c

···
 	 * says that this is the defacto standard.
 	 */
 	if (dmi_ver >= 0x020600)
-		sprintf(s, "%pUL", d);
+		sprintf(s, "%pUl", d);
 	else
-		sprintf(s, "%pUB", d);
+		sprintf(s, "%pUb", d);
 
 	dmi_ident[slot] = s;
 }