common: Fix two -Wold-style-declaration warnings.

This fixes the following warnings:

virtual_com.c:105:1: warning: 'static' is not at beginning of declaration
 volatile static uint32_t s_recvSize = 0;
 ^~~~~~~~
virtual_com.c:106:1: warning: 'static' is not at beginning of declaration
 volatile static uint8_t s_sendComplete = 0;
 ^~~~~~~~