ethernet/emac/sysrq: fix inconstistent help message of sysrq key

Currently help message of /proc/sysrq-trigger highlight its upper-case
characters, like below:

      SysRq : HELP : loglevel(0-9) reBoot Crash terminate-all-tasks(E)
      memory-full-oom-kill(F) kill-all-tasks(I) ...

this would confuse user trigger sysrq by upper-case character, which is
inconsistent with the real lower-case character registed key.

This inconsistent help message will also lead more confused when
26 upper-case letters put into use in future.

This patch ethernet emac sysrq key: "emac(c)"

Signed-off-by: zhangwei(Jovi) <jovi.zhangwei@huawei.com>
Cc: Josh Boyer <jwboyer@linux.vnet.ibm.com>
Cc: Thadeu Lima de Souza Cascardo <cascardo@linux.vnet.ibm.com>
Cc: David Miller <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>