i2c: bpmp-tegra: Ignore unknown I2C_M flags

In order to not to start returning errors when new I2C_M flags are
added, change behavior to just ignore all flags that we don't know
about. This includes the I2C_M_DMA_SAFE flag that already exists but
causes -EINVAL to be returned for valid transactions.

Cc: stable@vger.kernel.org # v4.19+
Signed-off-by: Mikko Perttunen <mperttunen@nvidia.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>