r600g: make condition clearer

r600g: make condition clearer

The second check in the old code looked pretty much unreachable, esp.
because it's not obvious that "max_entries" could be zero. To find out
that it was intentional I had to run some checks, and to dig into
the old versions of the file.

So, rewrite the check to make the intention clear.

v2: s/r600/r600g in the title, and per Dieter Nützel's comment wrap
lines of condition.

Signed-off-by: Constantine Kharlamov <Hi-Angel@yandex.ru>
Signed-off-by: Marek Olšák <marek.olsak@amd.com>
Acked-by: Dieter Nützel <Dieter@nuetzel-hh.de>
Tested-by: Dieter Nützel <Dieter@nuetzel-hh.de>