vulkan-samples: Disable overriding-option as error

vulkan-samples: Disable overriding-option as error

Clang complains/warns about mixing -ffp-contract=fast and -ffp-model=precise
lower this to warning only, this does not impact code generation, we still
get the diagnostic messge but wont break the build

Signed-off-by: Khem Raj <raj.khem@gmail.com>
Signed-off-by: Mathieu Dubois-Briand <mathieu.dubois-briand@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>