Remove manual flattening of pointerEvents in View

[javache]

Summary: Confirmed in https://github.com/facebook/react/commit/d779eba4b375134f373b7dfb9ea98d01c84bc48e that style properties already take priority over direct props, so we can avoid flattening style here.

Changelog: [General][Fixed] Small performance tweak to View wrapper to avoid unnecessary style flattening.

Reviewed By: sammy-SC

Differential Revision: D56740899