evas_vg_load_svg: Fix color parsing

Summary:
Remove unnecessary point movement in rgb(255, 255, 255) case in svg parsing.
In svg parsing, move the pointer by 'rgb(' before calling
_color_parser() in the rgb(255, 255, 255) case.
In function, string pointer moved unnecessary, so parsing is incorrect.
Therefore, remove unnecessary point movement.

Test Plan:
svg sample code
```
<svg xmlns:svg="http://www.w3.org/2000/svg" viewBox="0 0 300 300">
  <path d="M 0 0 h 200 v 200 z" style="fill:rgb(255, 155, 55);"/>
</svg>
```

before
{F4504779}

after
{F4504778}

Reviewers: Hermet

Subscribers: cedric, #reviewers, #committers

Tags: #efl

Differential Revision: https://phab.enlightenment.org/D12284

src/modules/evas/vg_loaders/svg/evas_vg_load_svg.c

@@ -337,7 +337,7 @@ _color_parser(const char *value, char **end)
 {
    double r;
 
-   r = eina_convert_strtod_c(value + 4, end);
+   r = eina_convert_strtod_c(value, end);
    *end = _skip_space(*end, NULL);
    if (**end == '%')
      r = 255 * r / 100;