staging: et131x: et1310_mac.c: ConfigMacStatRegs() add missing regs to be zeroed

The comment at the top of the function states 'we need to initialize all the macstat registers to zero', but not all macstat registers are zeroed. Zero the missing registers.
Tested on an ET-131x device.

Signed-off-by: Mark Einon <mark.einon@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>