EP_Size ($2D) - Return file size of File Entry

IN:
     A = EP_SIZE
   BHL = Pointer to File Entry in card at slot

OUT:
   Fc = 0, File Eprom available
        Fz = 1, File Entry marked as deleted
        Fz = 0, File Entry active
             CDE = size of file (24bit integer, C = high byte)

   Fc = 1,
        A = RC_ONF
        File Eprom was not found in slot, or File Entry not available

Registers changed after return:
   ..B...HL/IXIY same
   AF.CDE../.... different