changed p6 to p7 to be inline with MR3158

After making !3158 (merged) and chatting with @kliment1 I realized that naming the datasheet pins 7/8 pin6 would potentially be an issue, and I changed that footprint and the symbol MR accordingly to skip p6.

This MR is to get this footprint in sync with that.

This has made me think that the symbol MR may not be entirely necessary, as the S1G1S2G2D2D2D1D1 symbol would work for it, however the pin-count wouldn't match so maybe the symbol is nice to have regardless?