sunxi: dram: Add 'await_bits_clear'/'await_bits_set' helper functions

sunxi: dram: Add 'await_bits_clear'/'await_bits_set' helper functions

The old 'await_completion' function is not sufficient, because
in some cases we want to wait for bits to be cleared, and in the
other cases we want to wait for bits to be set. So split the
'await_completion' into two new 'await_bits_clear' and
'await_bits_set' functions.

Signed-off-by: Siarhei Siamashka <siarhei.siamashka@gmail.com>
Acked-by: Ian Campbell <ijc@hellion.org.uk>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>