libeffects: fix enum conversion warnings.

warning: implicit conversion from enumeration type 'LVDBE_Fs_en' to
different enumeration type 'LVM_Fs_en' [-Wenum-conversion]

Thanks to Luis Lozano for the patch!

BUG: None
Test: Compiles without warnings.
Change-Id: I5bb0b5fc2e4e23080f61a209ab0ea95f423bafb1