i2c: pasemi: Add registers bits and switch to BIT()

Add the missing register bits to the defines and also switch
those to use the BIT macro which is much more readable than
using hardcoded masks

Co-developed-by: Hector Martin <marcan@marcan.st>
Signed-off-by: Hector Martin <marcan@marcan.st>
Signed-off-by: Sven Peter <sven@svenpeter.dev>
Reviewed-by: Neal Gompa <neal@gompa.dev>
Reviewed-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>
Link: https://lore.kernel.org/r/20250222-pasemi-fixes-v1-1-d7ea33d50c5e@svenpeter.dev