I'd better set CROSS_COMPILE in the environment than change my path,
so CROSS_COMPILE is conditionally assigned.

The revision is better "git describe --dirty" than "git rev-parse". The output
is a short beautiful string like "wrpc-v2.0-13-g09a736d5"
with an optional "-dirty" trailer, to show we compiled a non-committed
change.

Finally, to execute commands we dont $(shell) at toplevel, but have
them in the build rule.
Signed-off-by: Alessandro Rubini <rubini@gnudd.com>

If you find this patch with "git blame" please use "git blame -w"
to have all white-space ignored while associating lines to commits.

This commit has no practical effect but cleanup. I made it
with sed like this:

  git grep -l '[ \t]$' | xargs sed -i 's/[ \t]*$//'

However, I had to manually restore doc/wrpc_mon.png after the fact.
Similarly, I restored the include/hw/*regs.h files, as they
are (most likely) auto-generated.

Read the MAC address either from EEPROM or sensor ID (preferring EEPROM).

This commit can be omitted when merging back to master, but not all the following commits.

Makefile: added Etherbone enable/disable switch, fixed --gc-sections linker arg (saves 6 kB of code)

Signed-off-by: Grzegorz Daniluk <g.daniluk@elproma.com.pl>

wrc_main: add sfp detection and getting its deltaTx/Rx from eeprom, not used now since sfps' parameters not known

It's only 1k.