skiboot: bump to v6.0.4

This bumps skiboot to the latest release.

Change-Id: I43ce295d67801d8196616871a21591abba7c82df
Signed-off-by: Joel Stanley <joel@jms.id.au>
diff --git a/common/recipes-bsp/skiboot/skiboot.inc b/common/recipes-bsp/skiboot/skiboot.inc
index 9a2b1e5..e4a275a 100644
--- a/common/recipes-bsp/skiboot/skiboot.inc
+++ b/common/recipes-bsp/skiboot/skiboot.inc
@@ -7,8 +7,8 @@
 
 LIC_FILES_CHKSUM = "file://${S}/LICENCE;md5=3b83ef96387f14655fc854ddc3c6bd57"
 
-SRCREV = "1d7da2e9b05b4995690abda54f853e0d84833af8"
-PV = "v5.10-rc3"
+SRCREV = "c55a54bbf38b6b3144105885e173ae7b6afab091"
+PV = "v6.0.4"
 
 S = "${WORKDIR}/git"