treewide: Remove "ERROR: "/"WARN: " prefixes from log messages

Now that the console system itself will clearly differentiate loglevels,
it is no longer necessary to explicitly add "ERROR: " in front of every
BIOS_ERR message to help it stand out more (and allow automated tooling
to grep for it). Removing all these extra .rodata characters should save
us a nice little amount of binary size.

This patch was created by running

  find src/ -type f -exec perl -0777 -pi -e 's/printk\(\s*BIOS_ERR,\s*"ERROR: /printk\(BIOS_ERR, "/gi' '{}' ';'

and doing some cursory review/cleanup on the result. Then doing the same
thing for BIOS_WARN with

  's/printk\(\s*BIOS_WARNING,\s*"WARN(ING)?: /printk\(BIOS_WARNING, "/gi'

Signed-off-by: Julius Werner <jwerner@chromium.org>
Change-Id: I3d0573acb23d2df53db6813cb1a5fc31b5357db8
Reviewed-on: https://review.coreboot.org/c/coreboot/+/61309
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: HAOUAS Elyes <ehaouas@noos.fr>
Reviewed-by: Lance Zhao
Reviewed-by: Jason Glenesk <jason.glenesk@gmail.com>

src/ec/google/chromeec/ec.c

@@ -975,7 +975,7 @@ int google_chromeec_vbnv_context(int is_read, uint8_t *data, int len)
 retry:
 
 	if (google_chromeec_command(&cmd)) {
-		printk(BIOS_ERR, "ERROR: failed to %s vbnv_ec context: %d\n",
+		printk(BIOS_ERR, "failed to %s vbnv_ec context: %d\n",
 			is_read ? "read" : "write", (int)cmd.cmd_code);
 		mdelay(10);	/* just in case */
 		if (--retries)