staging: vt6655: fix DBG_PRT and PRINT_K macros

Wrap both macros inside a 'do { ... } while(0)' to prevent breakage if
used within another 'if'. Also fix a usage of DBG_PRT with a missing
semicolon.

Signed-off-by: Guido Martínez <guido@vanguardiasur.com.ar>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>