reset: fix reset_get_by_index_nodev index handling

This fixes an issue getting resets index 1 and 3+, the spurius "> 0"
made it return the index 0 or 1, whatever index was passed.

The dm_test_reset_base() did not catch it, but the dm_test_reset_base() extension
catches it and this fixes the regression.

This also fixes a reggression on Amlogic G12A/G12B SoCs, where HDMI output was disable
even when Linux was booting.

Fixes: ea9dc35a ("reset: Get the RESET by index without device")
Reported-by: B1oHazard <ty3uk@mail.ua>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>