gpio/tca6424: merge I2C transactions, remove cast
gpio/tca6424: merge I2C transactions, remove cast

This is a follow-up to ae79c1904 "[PATCH v2] Add support for TCA6424"
merged in the v3.5 merge window.  It fixes comments made when the
patch was merged.
- Use 3 byte transfers instead of two separate transfers (2+1 byte)
- An unnecessary cast removed

Signed-off-by: Andreas Schallenberg <be8df24ca9de9a49da8d4e4b126d05a3d49e4c51@3alitytechnica.com>
Signed-off-by: Grant Likely <9069e6f5a2b566e2674a0ba1e2bf39c12c195fad@secretlab.ca>

KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs