Revert "temporary fix - add Ewk_Context to ewk_notification_showed to make WRT compile"

Revert "temporary fix - add Ewk_Context to ewk_notification_showed to make WRT compile"

This reverts commit 6e6015b9a35c2630454ec69f35d788571b854f1c.

Original commit message:
Context was not used and we removed it, but WRT assumes that
ewk_notification_showed takes context as one of the parameters
and after our Notification API refactoring it doesn't compile.
WRT will update to the new API, but for now we need this temporary
fix for it to work.
Reviewed by: Antonio Gomes, Daniel Waślicki, Hyunhak Kim

Change-Id: Ib3fe9036f8bfe2992d17e219a21213ed33bd6d90
Signed-off-by: yh106.jung <yh106.jung@samsung.com>