scripts/spelling.txt: add syfs/sysfs pattern

There are a few cases in the tree where "sysfs" is misspelled as "syfs".
Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@gmx.ne>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Colin Ian King <colin.king@canonical.com>
Cc: Xiong <xndchn@gmail.com>
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Chris Paterson <chris.paterson2@renesas.com>
Cc: Luca Ceresoli <luca@lucaceresoli.net>
Link: http://lkml.kernel.org/r/20200218152010.27349-1-j.neuschaefer@gmx.netSigned-off-by: Linus Torvalds <torvalds@linux-foundation.org>

scripts/spelling.txt

@@ -1328,6 +1328,7 @@ swithcing||switching
 swithed||switched
 swithing||switching
 swtich||switch
+syfs||sysfs
 symetric||symmetric
 synax||syntax
 synchonized||synchronized