MAINTAINERS: Update GENI I2C maintainers list

Alok Chauhan has moved out of GENI team, he no longer supports GENI I2C
driver, remove him from maintainer list.

Add Akash Asthana & Mukesh Savaliya as maintainers for GENI I2C drivers.

Signed-off-by: Akash Asthana <akashast@codeaurora.org>
Signed-off-by: Wolfram Sang <wsa@kernel.org>