Removed setting EPMM0 and EPMCS

[njh]

Change suggested by @mindstormsking in #134:
EPMM0 and EPMCS are used for pattern matching, but it is off by default and never switched on, so they are useless.

[vicatcu]

It looks to me like the pattern matching filters are enabled by

EtherCard/enc28j60.cpp

Line 388 in d502b45

writeRegByte(ERXFCON, ERXFCON_UCEN|ERXFCON_CRCEN|ERXFCON_PMEN|ERXFCON_BCEN);

OR'ing in ERXFCON_PMEN... I have no idea what motivated this pattern match filter to be there in the first place and a comment would have gone a long way to that end, but unless someone knows what this was intended to do and can articulate a reason for removing it, I think we should err on the side of not changing long-standing behavior that is not demonstrably a problem.

[mindstormsking]

The original code I changed had the following comment on the matter:

// For broadcast packets we allow only ARP packtets
// All other packets should be unicast only for our mac (MAADR)
//
// The pattern to match on is therefore
// Type ETH.DST
// ARP BROADCAST
// 06 08 -- ff ff ff ff ff ff -> ip checksum for theses bytes=f7f9
// in binary these poitions are:11 0000 0011 1111
// This is hex 303F->EPMM0=0x3f,EPMM1=0x30

But I don't see a direct reason why it could be removed. My change was probably useful four years ago, but I don't have a fast answer for you at this point and I probably will not go looking for it either...

[njh]

Closing this as a Won't Fix - I don't think there is enough motivation to investigate this further.