packaging: Make postinst scripts dash compatible

Debian Squeeze uses dash as the shell for systems scripts by default
and dash does not support the keyword "function" like bash does.

pkg/debian/postinst

@@ -36,7 +36,7 @@ fi
 
 # ----------------------------------------------------------------------
 
-function fn_config_replace 
+fn_config_replace ()
 {
 	if test $# -ne 2; then
 	  echo "Error - bad number of input parameters"

pkg/debian/ser-oob.postinst

@@ -35,7 +35,7 @@ if ! test -e $DEFAULTFILE; then
 fi
 
 
-function fn_config_replace 
+fn_config_replace ()
 {
 	if test $# -ne 2; then
 	  echo "Error - bad number of input parameters"