Add support for Microchip Technology's MCP3426/7/8 ADC

This patch extends previous mcp3422 driver to support
missing members of the family, mcp3426/7/8.

Signed-off-by: Angelo Compagnucci <angelo.compagnucci@gmail.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
2 files changed