hwmon: (w83792d) Fix NULL pointer dereference by removing unnecessary structure field

In the Linux kernel, the following vulnerability has been resolved:

hwmon: (w83792d) Fix NULL pointer dereference by removing unnecessary structure field

If driver read val value sufficient for

(val & 0x08) && (!(val & 0x80)) && ((val & 0x7) == ((val >> 4) & 0x7))

from device then Null pointer dereference occurs.

(It is possible if tmp = 0b0xyz1xyz, where same literals mean same numbers)

Also lm75[] does not serve a purpose anymore after switching to

devm_i2c_new_dummy_device() in w83791d_detect_subclients().

The patch fixes possible NULL pointer dereference by removing lm75[].

Found by Linux Driver Verification project (linuxtesting.org).

[groeck: Dropped unnecessary continuation lines, fixed multipline alignment]