Fix the register value comparison in the `max31335_volatile_reg`
function for the interrupt status register.

MAX31335_STATUS1 macro definition corresponds to the actual
interrupt status register.

Fixes: dedaf03b ("rtc: max31335: add driver support")
Signed-off-by: Antoniu Miclaus <antoniu.miclaus@analog.com>
Reviewed-by: Nuno Sa <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/20240219091616.24480-1-antoniu.miclaus@analog.comSigned-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>