net: ethernet: ocelot: remove the need for num_stats initializer

net: ethernet: ocelot: remove the need for num_stats initializer

There is a desire to share the oclot_stats_layout struct outside of the
current vsc7514 driver. In order to do so, the length of the array needs to
be known at compile time, and defined in the struct ocelot and struct
felix_info.

Since the array is defined in a .c file and would be declared in the header
file via:
extern struct ocelot_stat_layout[];
the size of the array will not be known at compile time to outside modules.

To fix this, remove the need for defining the number of stats at compile
time and allow this number to be determined at initialization.

Signed-off-by: Colin Foster <colin.foster@in-advantage.com>
Signed-off-by: David S. Miller <davem@davemloft.net>