platform/x86: topstar-laptop: remove sparse_keymap_free() calls

As sparse_keymap_setup() now uses a managed memory allocation for the
keymap copy it creates, the latter is freed automatically.  Remove all
calls to sparse_keymap_free().

Signed-off-by: Michał Kępień <kernel@kempniu.pl>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>