Kernel: Make device generate their own names

Besides removing the monolithic DevFSDeviceInode::determine_name()
method, being able to determine a device's name inside the /dev
hierarchy outside of DevFS has its uses.

Kernel/TTY/MasterPTY.cpp

@@ -141,4 +141,9 @@ String MasterPTY::absolute_path(const FileDescription&) const
     return String::formatted("ptm:{}", m_pts_name);
 }
 
+String MasterPTY::device_name() const
+{
+    return String::formatted("{}", minor());
+}
+
 }

Kernel/TTY/MasterPTY.h

@@ -50,6 +50,7 @@ public:
 
     // ^Device
     virtual mode_t required_mode() const override { return 0640; }
+    virtual String device_name() const override;
 
 private:
     // ^CharacterDevice

Kernel/TTY/PTYMultiplexer.h

@@ -57,6 +57,7 @@ public:
 
     // ^Device
     virtual mode_t required_mode() const override { return 0666; }
+    virtual String device_name() const override { return "ptmx"; }
 
 private:
     // ^CharacterDevice

Kernel/TTY/SlavePTY.cpp

@@ -106,6 +106,11 @@ KResult SlavePTY::close()
     return KSuccess;
 }
 
+String SlavePTY::device_name() const
+{
+    return String::formatted("{}", minor());
+}
+
 FileBlockCondition& SlavePTY::block_condition()
 {
     return m_master->block_condition();

Kernel/TTY/SlavePTY.h

@@ -57,6 +57,9 @@ private:
     virtual const char* class_name() const override { return "SlavePTY"; }
     virtual KResult close() override;
 
+    // ^Device
+    virtual String device_name() const override;
+
     friend class MasterPTY;
     SlavePTY(MasterPTY&, unsigned index);
 

Kernel/TTY/VirtualConsole.cpp

@@ -338,6 +338,11 @@ void VirtualConsole::emit(const u8* data, size_t size)
         TTY::emit(data[i]);
 }
 
+String VirtualConsole::device_name() const
+{
+    return String::formatted("tty{}", minor());
+}
+
 void VirtualConsole::echo(u8 ch)
 {
     if (should_echo_input()) {

Kernel/TTY/VirtualConsole.h

@@ -69,6 +69,9 @@ private:
     // ^CharacterDevice
     virtual const char* class_name() const override { return "VirtualConsole"; }
 
+    // ^Device
+    virtual String device_name() const override;
+
     void set_active(bool);
 
     void flush_vga_cursor();