gpio: sim: fix setting and getting multiple lines

We need to take mask into account in the set/get_multiple() callbacks.
Use bitmap_replace() instead of bitmap_copy().

Fixes: cb8c474e ("gpio: sim: new testing module")
Cc: stable@vger.kernel.org
Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>