get it out of a stuck condition that can be caused by GEM_MAC_RX_OVERFLOW.
- In gem_reset_rxdma() call gem_setladrf() in order to reprogram the RX
filter and restore the previous content of GEM_MAC_RX_CONFIG. While at it
consistently use the newly introduced sc_mac_rxcfg throughout the driver
instead of reading the its old content.
- Increment if_iqdrops instead of if_ierrors in case of RX buffer allocation
failure.
- According to the GEM datasheet the RX MAC should also be disabled in
gem_setladrf() before changing its configuration.
- Add error messages to gem_disable_{r,t}x() and take advantage of these
throughout the driver instead of duplicating their functionality all over
the place.
In joint forces with: yongari
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