ehea: make some functions and variables static

Some functions and variables in ehea are only used in their own file, so
they should be static. One particular function had a very generic name,
print_error_data.

Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>