[STM32F2-F4:CRYPTO]Fix hash_set_last_word_valid_bits()

/**
* @brief Configure the Number of valid bits in last word of the message
* @param ValidNumber: Number of valid bits in last word of the message.
* This parameter must be a number between 0 and 0x1F.
* - 0x00: All 32 bits of the last data written are valid
* - 0x01: Only bit [0] of the last data written is valid
* - 0x02: Only bits[1:0] of the last data written are valid
* - 0x03: Only bits[2:0] of the last data written are valid
* - ...
* - 0x1F: Only bits[30:0] of the last data written are valid
* @note The Number of valid bits must be set before to start the message
* digest competition (in Hash and HMAC) and key treatment(in HMAC).
* @retval None
*/

void HASH_SetLastWordValidBitsNbr(uint16_t ValidNumber)
{
/* Check the parameters */
assert_param(IS_HASH_VALIDBITSNUMBER(ValidNumber));
/* Configure the Number of valid bits in last word of the message */
HASH->STR &= ~(HASH_STR_NBW);
HASH->STR |= ValidNumber;
}

This from StdPeriph

P.S. No need subtraction.
just hash_set_last_word_valid_bits(8 * (len % 4))