sh_eth: fix *enum* {A|M}PR_BIT

The *enum* {A|M}PR_BIT were declared in the commit 86a74ff2 ("net:
sh_eth: add support for  Renesas SuperH Ethernet") adding SH771x support,
however the SH771x manual  doesn't have the APR/MPR registers described
and the code writing to them for SH7710 was later removed by the commit
380af9e3

 ("net: sh_eth: CPU dependency code collect to "struct
sh_eth_cpu_data""). All the newer SoC manuals have these registers
documented as having a 16-bit TIME parameter of the PAUSE frame, not
1-bit -- update the *enum* accordingly, fixing up the APR/MPR writes...

Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: David S. Miller <davem@davemloft.net>