iio: Fix sign extension table in mcp3422 driver
iio: Fix sign extension table in mcp3422 driver

the index argument to sign_extend32() gives the bit position (from 0)
to the sign bit

so e.g. if the measurement has 16-bit resolution, we need to pass 15;
a measurement of 0x8000 should be reported as -32768, not 32768

Signed-off-by: Peter Meerwald <a2c19d57d338d8f9d8de092166164455662a8cbe@pmeerw.net>
Acked-by: Angelo Compagnucci <9118629b2d65c9a0b93a5821e195ab758351ff75@gmail.com>
Signed-off-by: Jonathan Cameron <09f65b71b7655725897b2fd41a09a0cefe2e1ace@kernel.org>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs