iio:pressure: Add STMicroelectronics pressures driver

This patch adds a generic pressure driver for STMicroelectronics
pressure sensors, currently it supports: LPS331AP.

Signed-off-by: Denis Ciocca <denis.ciocca@st.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
diff --git a/drivers/iio/Kconfig b/drivers/iio/Kconfig
index daa3ddd..9af763a 100644
--- a/drivers/iio/Kconfig
+++ b/drivers/iio/Kconfig
@@ -73,5 +73,6 @@
 if IIO_TRIGGER
    source "drivers/iio/trigger/Kconfig"
 endif #IIO_TRIGGER
+source "drivers/iio/pressure/Kconfig"
 
 endif # IIO