i2c: npcm7xx: Fix typos

The comments in this driver have a few typos. Let's fix them.

Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net>
Reviewed-by: Randy Dunlap <rdunlap@infradead.org>
Reviewed-by:  <tali.perry@nuvoton.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>