meta-inspur: Cleanup for Yocto override syntax change

Refer to: https://lore.kernel.org/openbmc/YQ1FD5q8KbhbXVBK@heinlein/

```
poky/scripts/contrib/convert-overrides.py meta-inspur

git grep "_[a-z0-9_/-]*[ :]" -- meta-inspur | grep ".bb"

git grep -l _fp5280g2 -- meta-inspur | xargs sed -i \
's/_fp5280g2/:fp5280g2/'
git grep -l _on5263m5 -- meta-inspur | xargs sed -i \
's/_on5263m5/:on5263m5/'
git grep -l _virtual  -- meta-inspur | xargs sed -i \
's/_virtual/:virtual/'

```

Signed-off-by: George Liu <liuxiwei@inspur.com>
Change-Id: I5ef5039691caf5e33fb865da0fdd70d95d7e3bdf
diff --git a/meta-inspur/meta-fp5280g2/recipes-phosphor/fans/phosphor-fan-control-fan-config.bbappend b/meta-inspur/meta-fp5280g2/recipes-phosphor/fans/phosphor-fan-control-fan-config.bbappend
index a5847a6..f48eef4 100644
--- a/meta-inspur/meta-fp5280g2/recipes-phosphor/fans/phosphor-fan-control-fan-config.bbappend
+++ b/meta-inspur/meta-fp5280g2/recipes-phosphor/fans/phosphor-fan-control-fan-config.bbappend
@@ -1 +1 @@
-FILESEXTRAPATHS_prepend_fp5280g2 := "${THISDIR}/${BPN}:"
+FILESEXTRAPATHS:prepend:fp5280g2 := "${THISDIR}/${BPN}:"