package/live555: fix build config with locale

Using current conditional code, added in 2014:

ifndef ($(BR2_ENABLE_LOCALE),y)
LIVE555_CFLAGS += -DLOCALE_NOT_USED
endif

the define LOCALE_NOT_USED is always passed on CFLAGS, because there is
no symbol with following names defined:
 "(y,y)" -> not defined when BR2_ENABLE_LOCALE=y
 "(,y)" -> not defined when BR2_ENABLE_LOCALE is not set

So fix the typo, switching ifndef to ifneq.

Signed-off-by: Ricardo Martincoski <ricardo.martincoski@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>