treewide: reduce append operators on SRC_URI

In a base bb file where we are setting the primary git repository, it
is rare that we need to `SRC_URI +=`.  This is an unnecessary pattern
that seems to have been copied throughout the repository.  Remove the
pattern where appropriate and simply set SRC_URI directly.

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I430186a82f9582ba6196f5bf66b659af4092b48d
diff --git a/meta-phosphor/recipes-phosphor/dbus-top/dbus-top_git.bb b/meta-phosphor/recipes-phosphor/dbus-top/dbus-top_git.bb
index 260047a..8114e5c 100644
--- a/meta-phosphor/recipes-phosphor/dbus-top/dbus-top_git.bb
+++ b/meta-phosphor/recipes-phosphor/dbus-top/dbus-top_git.bb
@@ -5,7 +5,7 @@
 LICENSE = "Apache-2.0"
 LIC_FILES_CHKSUM = "file://LICENSE;md5=e3fc50a88d0a364313df4b21ef20c29e"
 
-SRC_URI += "git://github.com/openbmc/dbus-top;protocol=https;branch=main"
+SRC_URI = "git://github.com/openbmc/dbus-top;protocol=https;branch=main"
 SRCREV = "abc3218cc2a9fe2de9fc9db214749b89f30c1774"
 
 S = "${WORKDIR}/git"