mfd: cpcap: Fix bad use of IRQ sense register

The cpcap INTS registers are for getting the value of the line,
not for configuring the type.

Fixes: 56e1d40d

 ("mfd: cpcap: Add minimal support")
Reviewed-By: Sebastian Reichel <sre@kernel.org>
Tested-by: Sebastian Reichel <sre@kernel.org>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>