macintosh: windfarm: Use unsigned type for 1-bit bitfields

Clang warns:

  drivers/macintosh/windfarm_lm75_sensor.c:63:14: error: implicit truncation from 'int' to a one-bit wide bit-field changes value from 1 to -1 [-Werror,-Wsingle-bit-bitfield-constant-conversion]
                  lm->inited = 1;
                             ^ ~

  drivers/macintosh/windfarm_smu_sensors.c:356:19: error: implicit truncation from 'int' to a one-bit wide bit-field changes value from 1 to -1 [-Werror,-Wsingle-bit-bitfield-constant-conversion]
                  pow->fake_volts = 1;
                                  ^ ~
  drivers/macintosh/windfarm_smu_sensors.c:368:18: error: implicit truncation from 'int' to a one-bit wide bit-field changes value from 1 to -1 [-Werror,-Wsingle-bit-bitfield-constant-conversion]
                  pow->quadratic = 1;
                                 ^ ~

There is no bug here since no code checks the actual value of these
fields, just whether or not they are zero (boolean context), but this
can be easily fixed by switching to an unsigned type.

Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20230215-windfarm-wsingle-bit-bitfield-constant-conversion-v1-1-26415072e855@kernel.org