Bump to version 609ad51

This includes the following changes:

609ad51 swupdate-progress: Terminate bar array string
9aa4bbe lua: Prevent mtdname and path from clobbering each other
57f64a9 core/artifacts_version: Don't concat version
b060243 core/artifacts_version: Fix infinite loop in is_oldstyle_version()

Signed-off-by: Stefano Babic <sbabic@denx.de>

recipes-support/swupdate/swupdate_git.bb

@@ -2,5 +2,5 @@ require swupdate.inc
 
 DEFAULT_PREFERENCE = "-1"
 
-SRCREV ?= "0c672866d4a9fe8f0808b5d8a0afb95c13c4c138"
+SRCREV ?= "20c30531b6be6e379aafb1425d56481578f36c1b"
 PV = "2020.04+git${SRCPV}"