[FIX] web: properly apply css in mobile search view

In some cases, if the device is in a mobile mode, but does not support
touch, then the mobile search view is shown, as expected, but the css
is not applied.

Maybe this is not a big deal in practice, since the only way to notice this is
to use odoo on a browser with a small window and no touch emulation, but
this is still annoying and wrong: if the mobile search view is
displayed, the its css should be applied in all cases.

We simply fix the css rule to make it work like expected.

addons/web/static/src/scss/search_view_mobile.scss

@@ -1,4 +1,4 @@
-.o_web_client.o_touch_device {
+.o_web_client {
     .o_mobile_search {
         position: fixed;
         top: 0;