sensor: isl29035: Unchecked return value
sensor: isl29035: Unchecked return value

Check the return value of i2c_reg_read_byte() and return
if unable to read the register
Coverity-CID: 188740

Fixes #10585

Signed-off-by: Satya Bhattacharya <205a52cde0838756f29cc163a6b8555bffb1fbe1@gmail.com>

explora26/zephyr,ldts/zephyr,GiulianoFranchetto/zephyr,Vudentz/zephyr,Vudentz/zephyr,nashif/zephyr,zephyrproject-rtos/zephyr,nashif/zephyr,nashif/zephyr,finikorg/zephyr,ldts/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,finikorg/zephyr,ldts/zephyr,galak/zephyr,punitvara/zephyr,galak/zephyr,punitvara/zephyr,zephyrproject-rtos/zephyr,Vudentz/zephyr,explora26/zephyr,punitvara/zephyr,GiulianoFranchetto/zephyr,nashif/zephyr,GiulianoFranchetto/zephyr,finikorg/zephyr,Vudentz/zephyr,punitvara/zephyr,punitvara/zephyr,GiulianoFranchetto/zephyr,explora26/zephyr,galak/zephyr,explora26/zephyr,GiulianoFranchetto/zephyr,Vudentz/zephyr,ldts/zephyr,finikorg/zephyr,galak/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,ldts/zephyr,nashif/zephyr,explora26/zephyr,Vudentz/zephyr