OPAL_TEST
---------

OPAL_TEST is a REQUIRED call for OPAL and conforming implementations MUST
have it.

It is designed to test basic OPAL call functionality.

Token:
#define OPAL_TEST				0

Arguments:
	uint64_t	arg

Returns:
	0xfeedf00d


Function:
OPAL_TEST MAY print a string to the OPAL log with the value of argument.

For example, the reference implementation (skiboot) implements OPAL_TEST as:

static uint64_t opal_test_func(uint64_t arg)
{
        printf("OPAL: Test function called with arg 0x%llx\n", arg);

        return 0xfeedf00d;
}