Do not parse --max-fps float in the client

Many parsing and formatting C functions like strtof() and asprintf() are
locale-dependent. Forcing a C locale just for the conversions in a way
that works on all platforms is a mess.

In practice, this is not a problem, scrcpy always uses the C locale,
because it never calls:

    setlocale(LC_ALL, "");

But the max-fps option should not depend on the locale configuration
anyway.

Since the value is parsed by the client in Java anyway, just forward the
string value as is.