• Correct collision counter for BCM5705+. This register is read/clear.
• Correct RX packet drop counter for BCM5705+. This register is read/clear

and it wraps very quickly under heavy packet drops because only the lower
ten bits are valid according to the documentation. However, it seems few
more bits are actually valid and the rest bits are always zeros[1].
Therefore, we don't mask them off here. To get accurate packet drop count,
we need to check the register from bge_rxeof(). It is commented out for now,
not to penalize normal operation. Actual performance impact should be
measured later.

• Correct integer casting from u_long to uint32_t. Casting is not really

needed for all supported platforms but we better do this correctly[2].

Tested by: bde[1]
Suggested by: bde[2]