bswap.h: Remove unused float-access functions

bswap.h: Remove unused float-access functions

The float-access functions stfl_*, stfq*, ldfl* and ldfq* are now
unused; remove them.  (Accesses to float64 and float32 types can be
made with the ldl/stl/ldq/stq functions, as float64 and float32 are
guaranteed to be typedefs for normal integer types.)

Signed-off-by: Peter Maydell <[email protected]>
Signed-off-by: Alex Bennée <[email protected]>
Reviewed-by: Philippe Mathieu-Daudé <[email protected]>
Message-Id: <20210208113428[email protected]>
Message-Id: <20210211122750[email protected]>