mei: amthif: drop parameter validation from mei_amthif_write

Remove duplicated parameter validation from mei_amthif_write functions,
The parameter check is already performed by the caller function
mei_write

Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Alexander Usyskin <alexander.usyskin@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>