loader: implement MEDIA_FILEPATH_DP support in efipart

[tsoome]

Summary

The efipart rework did break the ARM systems as the new code is
using more exact filters to sort the devices and we need to
add support for MEDIA_FILEPATH_DP device paths.

Test Plan

Need to verify on ARM platform.

[allanjude]

Once you get someone to verify this works on an ARM device, approved.

[tsoome]

In D9520#196825, @allanjude wrote:

Once you get someone to verify this works on an ARM device, approved.

It actually does need some more work - while device mapping appears to be OK, there is still something about mapping device path from image handle. Meaning, this snippet is not yet full fix.

[gonzo]

I tested it on rpi3, it works with crochet-generated image

OK  lsdev
disk devices:
    disk0:    15564801 X 512 blocks (removable)
      disk0s1: DOS/Windows
      disk0s2: FreeBSD
        disk0s2a: FreeBSD UFS
net devices:
    net0:

[tsoome]

In D9520#196965, @gonzo wrote:

I tested it on rpi3, it works with crochet-generated image

OK  lsdev
disk devices:
    disk0:    15564801 X 512 blocks (removable)
      disk0s1: DOS/Windows
      disk0s2: FreeBSD
        disk0s2a: FreeBSD UFS
net devices:
    net0:

does it actually boot properly in your case?

[gonzo]

In D9520#196967, @tsoome wrote:

In D9520#196965, @gonzo wrote:

I tested it on rpi3, it works with crochet-generated image

... skipped ...

does it actually boot properly in your case?

Yes, it boots to login prompt

[manu]

As I said on IRC on #bsdmips I don't know if u-boot is doing the right thing on disk (and by u-boot I mean me since I've done the patch for logical partition).
But it used to work before so if one commit broke it and this review restore the func I'm up for it.
Note that I didn't test the patch. It just looks sane for me.