Addition of support for ADLX312 and ADXL314 for the ADXL313 driver.

[danmois]

ADXL312 and ADXL314 are small, thin, low power, 3-axis accelerometers with high resolution (13-bit) measurement up to +/-12 g and +/- 200 g, respectively. They are based on the same ASIC as ADXL313 and support for their operation is added to the already existing ADXL313 driver.

[danmois]

V1

• added the scale_factor member for driver data
• added an array for regmaps associated to every device
• replaced the condition for future proofing

[danmois]

V2

• implemented Checkpatch Script suggested fixes

[danmois]

V3

• implemented review comments (removed unrelated change, extra lines, unnecessary brackets)

[nunojsa]

I think these patches can be sent upstream for further review.

Surely the way to go in here. Please send these upstream before merging them in our tree.

[danmois]

V4

• variant accepted upstream