Kernel: Use operator ""sv in all class_name() implementations

Previously there was a mix of returning plain strings and returning
explicit string views using `operator ""sv`. This change switches them
all to standardized on `operator ""sv` as it avoids a call to strlen.

Kernel/Storage/Partition/DiskPartition.cpp

@@ -77,7 +77,7 @@ bool DiskPartition::can_write(const OpenFileDescription& fd, size_t offset) cons
 
 StringView DiskPartition::class_name() const
 {
-    return "DiskPartition";
+    return "DiskPartition"sv;
 }
 
 }