skiboot: Use commit SHA instead of tag.

Using a tag forces bitbake to go out and try to contact the source
even if the repo has been downloaded in mirror tarball. It prevents
building on a machine without network access using a local mirror.

Change-Id: I71a984fc784ada82fa81294917c9e2fbc0a4935b
Signed-off-by: yuenn <yuenn@google.com>
diff --git a/meta-openbmc-machines/meta-openpower/common/recipes-bsp/skiboot/skiboot.inc b/meta-openbmc-machines/meta-openpower/common/recipes-bsp/skiboot/skiboot.inc
index 60fc4a1..bb8e058 100644
--- a/meta-openbmc-machines/meta-openpower/common/recipes-bsp/skiboot/skiboot.inc
+++ b/meta-openbmc-machines/meta-openpower/common/recipes-bsp/skiboot/skiboot.inc
@@ -8,7 +8,7 @@
 
 LIC_FILES_CHKSUM = "file://${S}/LICENCE;md5=3b83ef96387f14655fc854ddc3c6bd57"
 
-SRCREV = "v5.7-rc2"
+SRCREV = "da6ff8b098765434f21880e81ed4e324dacd0f49"
 PV = "v5.7-rc2"
 
 S = "${WORKDIR}/git"