vty: fix 'show lchan ...' arg [lchan_nr] to [<0-7>]

A lower-case argument is a keyword, not a variable placeholder. Hence the user
would not be able to pass a number, just the "lchan_nr" string itself, hence
this would never work.

Depending on pchan, lchans can range 0..7, so use that instead.

Change-Id: Ib9a0b43b68c4682cd6de24d01c0de421c9ce957a
diff --git a/src/libbsc/bsc_vty.c b/src/libbsc/bsc_vty.c
index e60bdaf..dcdd28a 100644
--- a/src/libbsc/bsc_vty.c
+++ b/src/libbsc/bsc_vty.c
@@ -1297,7 +1297,7 @@
 
 DEFUN(show_lchan,
       show_lchan_cmd,
-      "show lchan [<0-255>] [<0-255>] [<0-7>] [lchan_nr]",
+      "show lchan [<0-255>] [<0-255>] [<0-7>] [<0-7>]",
 	SHOW_STR "Display information about a logical channel\n"
 	"BTS Number\n" "TRX Number\n" "Timeslot Number\n"
 	LCHAN_NR_STR)
@@ -1308,7 +1308,7 @@
 
 DEFUN(show_lchan_summary,
       show_lchan_summary_cmd,
-      "show lchan summary [<0-255>] [<0-255>] [<0-7>] [lchan_nr]",
+      "show lchan summary [<0-255>] [<0-255>] [<0-7>] [<0-7>]",
 	SHOW_STR "Display information about a logical channel\n"
         "Short summary\n"
 	"BTS Number\n" "TRX Number\n" "Timeslot Number\n"