vg_common_svg: Gradient stop color use premultiplied color.

Summary:
The parsed color is straight color.
evas use premultiplied color.

Test Plan:
Sample SVG
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 100 100">
  <defs>
    <linearGradient id="linearGradient1" x1="0" y1="0" x2="0.2" y2="0.2" spreadMethod="reflect">
      <stop style="stop-color:#ff0000;stop-opacity:1;" offset="0"/>
      <stop style="stop-color:#0000ff;stop-opacity:1;" offset="1"/>
    </linearGradient>
    <radialGradient id="radialGradient222" r="0.2" cx="0.3" cy="0.3" spreadMethod="reflect">
      <stop style="stop-color:#ffFF00;stop-opacity:0.1;" offset="0"/>
      <stop style="stop-color:#00FFff;stop-opacity:1;"   offset="1"/>
    </radialGradient>
    <radialGradient id="radialGradient333" r="0.2" cx="0.3" cy="0.3" spreadMethod="reflect">
      <stop style="stop-color:#00FF00;stop-opacity:0.1;" offset="0"/>
      <stop style="stop-color:#FF00ff;stop-opacity:1;"   offset="1"/>
    </radialGradient>
   </defs>
  <rect x="0" y="0" width="100" height="100" fill="url(#linearGradient1)"/>
  <rect x="50" y="50" width="50" height="50" fill="url(#radialGradient222)"/>
  <rect x="0" y="0" width="50" height="50" fill="url(#radialGradient333)"/>
</svg>

Reviewers: Hermet, kimcinoo, smohanty

Reviewed By: Hermet

Subscribers: cedric, #reviewers, #committers

Tags: #efl

Differential Revision: https://phab.enlightenment.org/D9338