scripts/spelling.txt: add "varible" pattern and fix typo instances

Fix typos and add the following to the scripts/spelling.txt:

  varible||variable

While we are here, tidy up the comment blocks that fit in a single line
for drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c and
net/sctp/transport.c.

Link: http://lkml.kernel.org/r/1481573103-11329-11-git-send-email-yamada.masahiro@socionext.com
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/Documentation/scsi/ChangeLog.megaraid_sas b/Documentation/scsi/ChangeLog.megaraid_sas
index 00ffdf18..234ddab 100644
--- a/Documentation/scsi/ChangeLog.megaraid_sas
+++ b/Documentation/scsi/ChangeLog.megaraid_sas
@@ -549,7 +549,7 @@
 3 Older Version   : 00.00.03.02
 
 i.	Send stop adapter to FW & Dump pending FW cmds before declaring adapter dead.
-	New varible added to set dbg level.
+	New variable added to set dbg level.
 ii.	Disable interrupt made as fn pointer as they are different for 1068 / 1078
 iii.	Frame count optimization. Main frame can contain 2 SGE for 64 bit SGLs and
 	3 SGE for 32 bit SGL