target/sh4: fix some comment spelling errors

There are many spelling errors in the comments of target/sh4.
Use spellcheck to check the spelling errors, then fix them.

Signed-off-by: zhaolichang <zhaolichang@huawei.com>
Reviewed-by: David Edmondson <david.edmondson@oracle.com>
Reviewed-by: Philippe <Mathieu-Daude&lt;f4bug@amsat.org>
Message-Id: <20201009064449.2336-10-zhaolichang@huawei.com>
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>