fix(avatar): icon size (#1758)

Co-authored-by: maxin <maxin@growingio.com>

src/avatar/style/index.less

@@ -19,7 +19,7 @@
     background-color: rgba(36, 46, 89, 0.5);
     border: 1px solid @gray-0;
     border-radius: 100%;
-    span {
+    > span {
       transform: scale(1);
     }
   }
@@ -55,7 +55,7 @@
     text-align: center;
     background-color: transparent;
     cursor: pointer;
-    span {
+    > span {
       vertical-align: middle;
       transform: scale(0);
       transition: all 0.3s;
@@ -68,7 +68,7 @@
     transform-origin: 0 center;
   }
 
-  img {
+  > img {
     position: relative;
     display: block;
     width: 100%;
@@ -102,12 +102,6 @@
           color: @blue-2;
         }
       }
-      .@{avatar-prefix-cls}-icon {
-        & svg {
-          width: 12px;
-          height: 12px;
-        }
-      }
     }
   }
 
@@ -137,12 +131,6 @@
           color: @blue-2;
         }
       }
-      .@{avatar-prefix-cls}-icon {
-        & svg {
-          width: 16px;
-          height: 16px;
-        }
-      }
     }
   }
 
@@ -173,12 +161,6 @@
           color: @blue-2;
         }
       }
-      .@{avatar-prefix-cls}-icon {
-        & svg {
-          width: 28px;
-          height: 28px;
-        }
-      }
     }
   }
 
@@ -208,20 +190,14 @@
           color: @blue-2;
         }
       }
-      .@{avatar-prefix-cls}-icon {
-        & svg {
-          width: 40px;
-          height: 40px;
-        }
-      }
     }
   }
 
   &-group {
     display: flex;
     .@{avatar-prefix-cls} {
       border: 1.4px solid @gray-0;
-      span {
+      > span {
         top: -1.5px;
       }
       &:hover {