kernel: Name the scoped lock in ATADevice::read()

Is that supposed to work without a name? Looks like it did!

kernel/src/arch/x86_64/disk/ATA.cpp

@@ -748,7 +748,7 @@ Result<u64> ATADevice::read(u8* buf, usize offset, usize size) const
 
     auto block_size = m_drive->block_size();
 
-    ScopedKMutexLock<100>(m_drive->channel()->lock());
+    ScopedKMutexLock<100> lock(m_drive->channel()->lock());
 
     // FIXME: Don't always allocate this if we don't need it.
     auto* temp = TRY(make_array<u8>(block_size));