Modify overlay and add driver for Chipdip DAC

[chipdipru]

The overlay has been changed and driver has been added for Chipdip DAC, tested on Raspberry PI3.

[pelwell]

There are some cosmetic (whitespace) issues, but basically this looks fine. Please fix the whitespace, then squash the changes to make three commits:

1. The driver and its Makefile and Kconfig changes.
2. The overlay and its Makefile and README changes.
3. The updated _defconfig files with "SND_BCM2708_SOC_CHIPDIP_DAC=m" (you can grab this from here: pelwell@2476771)

[chipdipru]

Phil, thanks for the review, corrections have been made.

[pelwell]

The driver C file has ended up with DOS line endings (CR+LF), whereas Linux line endings should be just LF. Also, delete any trailing whitespace.

Once you've done that, squash the commits down to the three I described above.

[pelwell]

I've fixed up the commits for you. Write three commit messages here in code sections - like this:

First commit message

This is the first commit.

Signed-off-by: User Name <user@email.com>

I can graft them on and merge the PR.

[chipdipru]

Thank you. I am not sure I understand what I shall do. Please correct me if something is wrong.

Update and rename chipdip-i2s-master-dac-overlay

Simple card fragment removed, GPIO fragment added.

Signed-off-by: Evgenij Sapunov <evgenij.sapunov@chipdip.ru>

Add chipdip-dac driver

Driver chipdip-dac.c added into sound/soc/bcm/, files sound/soc/bcm/Kconfig and sound/soc/bcm/Makefile updated

Signed-off-by: Evgenij Sapunov <evgenij.sapunov@chipdip.ru>

Update _defconfig files

Files arch/arm/configs/bcm2709_defconfig, arch/arm/configs/bcm2711_defconfig, arch/arm/configs/bcmrpi_defconfig, arch/arm64/configs/bcm2711_defconfig, arch/arm64/configs/bcmrpi3_defconfig updated.

Signed-off-by: Evgenij Sapunov <evgenij.sapunov@chipdip.ru>

[pelwell]

That's perfect.

I'm guessing that either you are using the GitHub GUI for creating your pull requests or you haven't discovered git rebase -i. I recommend taking the time to learn how to edit and squash commits, then using git push -f to update the branch you created your PR from until it looks correct - it will save you a lot of time in the future.

[chipdipru]

Thank you!