[ticket/11030] Fixing cursor appearing in file upload browse button.

Removed unnecessary cursor CSS properties added for form inputs in both acp
and prosilver styles. Added cursor:pointer property only for buttons.

PHPBB3-11030
[ticket/11030] Fix cursor for checkboxes

PHPBB3-11030
Merge pull request #1840 from cyberalien/ticket/11030

Fix cursor in prosilver and ACP