w: Remove unreachable l option code

@ruihongw quite rightly pointed out we removed the l option
from the man page and getopt but the iunreachable case statement
remained.

References:
 commit 94468ac0b3
 #162

Signed-off-by: Craig Small <csmall@dropbear.xyz>

w.c

@@ -588,9 +588,6 @@ int main(int argc, char **argv)
 		case 'h':
 			header = 0;
 			break;
-		case 'l':
-			longform = 1;
-			break;
 		case 's':
 			longform = 0;
 			break;