[Snek] [keith-packard/snek] 79b525: metro-snek: Mask in unchanged pincfg bits instead ...

[Keith Packard]

  Branch: refs/heads/master
  Home:   https://github.com/keith-packard/snek
  Commit: 79b525addf71caacb08c50a738d8a2e1fb9cb36e
      https://github.com/keith-packard/snek/commit/79b525addf71caacb08c50a738d8a2e1fb9cb36e
  Author: Keith Packard <keithp at keithp.com>
  Date:   2019-04-11 (Thu, 11 Apr 2019)

  Changed paths:
    M metro-snek/samd21.h

  Log Message:
  -----------
  metro-snek: Mask in unchanged pincfg bits instead of changed bits

When modifying pincfg bits, use the provided mask as a set of bits to
clear from the old value, leaving all other bits unchanged.

Signed-off-by: Keith Packard <keithp at keithp.com>