[client] egl: remove needless precision quantifiers

We simply use precision mediump float; for everything. We don't actually
need highp anyways, and we don't use it for stuff like CAS or FSR.

client/renderers/EGL/shader/cursor_mono.frag

@@ -1,13 +1,14 @@
 #version 300 es
+precision mediump float;
 
-in  highp vec2 uv;
-out highp vec4 color;
+in  vec2 uv;
+out vec4 color;
 
 uniform sampler2D sampler1;
 
 void main()
 {
-  highp vec4 tmp = texture(sampler1, uv);
+  vec4 tmp = texture(sampler1, uv);
   if (tmp.rgb == vec3(0.0, 0.0, 0.0))
     discard;
   color = tmp;