hwmon: lis3: use block read to access data registers

Add optional blockread function to interface driver. If available
the chip driver uses it for data register access. For 12 bit device
it reads 6 bytes to get 3*16bit data. For 8 bit device it reads out
5 bytes since every second byte is dummy.
This optimizes bus usage and reduces number of operations and
interrupts needed for one data update.

Signed-off-by: Samu Onkalo <samu.p.onkalo@nokia.com>
Acked-by: Jonathan Cameron <jic23@cam.ac.uk>
Acked-by: Eric Piel <eric.piel@tremplin-utc.net>
Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>

include/linux/lis3lv02d.h

@@ -68,6 +68,7 @@ struct lis3lv02d_platform_data {
 	s8 axis_y;
 	s8 axis_z;
 #define LIS3_USE_REGULATOR_CTRL 0x01
+#define LIS3_USE_BLOCK_READ	0x02
 	u16 driver_features;
 	int default_rate;
 	int (*setup_resources)(void);