soc/intel/common/block/cse: Change loglevel prefix to WARNING

This message is not really an error message, so BIOS_ERR is
inappropriate. The message does seem more like a warning though,
that the developer could have multiple Kconfigs selected to send EOP,
therefore switch to BIOS_WARN instead.

BRANCH=firmware-brya-14505.B
TEST=build

Signed-off-by: Wisley Chen <wisley.chen@quanta.corp-partner.google.com>
Change-Id: I57a34334007a6a7443302c2f25de3d5c87c85573
Reviewed-on: https://review.coreboot.org/c/coreboot/+/62820
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Subrata Banik <subratabanik@google.com>

src/soc/intel/common/block/cse/cse_eop.c

@@ -204,7 +204,7 @@ static void do_send_end_of_post(void)
 	static bool eop_sent = false;
 
 	if (eop_sent) {
-		printk(BIOS_ERR, "EOP already sent\n");
+		printk(BIOS_WARNING, "EOP already sent\n");
 		return;
 	}