staging: r8188eu: make blink interval defines internal

The defines for led blink intervals are used only by the led layer.
Move them into rtw_led.c.

Signed-off-by: Martin Kaiser <martin@kaiser.cx>
Link: https://lore.kernel.org/r/20211226195556.159471-12-martin@kaiser.cx


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>