patch 8.2.3914: various spelling mistakes in comments

Problem:    Various spelling mistakes in comments.
Solution:   Fix the mistakes. (Dominique Pellé, closes #9416)
diff --git a/src/os_amiga.c b/src/os_amiga.c
index 18f0192..5bf088b 100644
--- a/src/os_amiga.c
+++ b/src/os_amiga.c
@@ -153,7 +153,7 @@
 mch_inchar(
     char_u  *buf,
     int	    maxlen,
-    long    time,		// milli seconds
+    long    time,		// milliseconds
     int	    tb_change_cnt)
 {
     int	    len;