[S] Change in coreboot[master]: soc/amd/[glinda|morgana]: Enable override of MAINBOARD_BLOBS_DIR

[Matt DeVillier (Code Review)]

Attention is currently required from: Jason Glenesk, Fred Reitberger, Felix Held.

Matt DeVillier has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/69410 )

Change subject: soc/amd/[glinda|morgana]: Enable override of MAINBOARD_BLOBS_DIR
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Patch Set 1:

(1 comment)

File src/soc/amd/glinda/Makefile.inc:

https://review.coreboot.org/c/coreboot/+/69410/comment/16d6bd42_57ff493e 
PS1, Line 61: MAINBOARD_BLOBS_DIR:=$
we already do this for MDN which is fine, but it seems a little odd to me that we define the MAINBOARD_BLOBS_DIR at the SoC level, identically for each SoC. Perhaps it can be moved to a common location?