sparc: Pass buffer pointer all the way down to prom_{get,put}char().

sparc: Pass buffer pointer all the way down to prom_{get,put}char().

[ Upstream commit e62cac1fd035b4cde707285008499dbe71955a86 ]

This gets us closer to being able to eliminate the use
of dynamic and stack based buffers, so that we can adhere
to the "no buffer addresses above 4GB" rule for PROM calls.

Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>