powerpc/embedded6xx: Fix no previous prototype for avr_uart_send() etc.

Move the prototypes into mpc10x.h which is included by all the relevant
C files, fixes:

  arch/powerpc/platforms/embedded6xx/ls_uart.c:59:6: error: no previous prototype for 'avr_uart_configure'
  arch/powerpc/platforms/embedded6xx/ls_uart.c:82:6: error: no previous prototype for 'avr_uart_send'

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20240305123410.3306253-1-mpe@ellerman.id.au

Author: mpe

arch/powerpc/platforms/embedded6xx/linkstation.c

@@ -99,9 +99,6 @@ static void __init linkstation_init_IRQ(void)
 	mpic_init(mpic);
 }
 
-extern void avr_uart_configure(void);
-extern void avr_uart_send(const char);
-
 static void __noreturn linkstation_restart(char *cmd)
 {
 	local_irq_disable();

arch/powerpc/platforms/embedded6xx/mpc10x.h

@@ -156,4 +156,7 @@ int mpc10x_disable_store_gathering(struct pci_controller *hose);
 /* For MPC107 boards that use the built-in openpic */
 void mpc10x_set_openpic(void);
 
+void avr_uart_configure(void);
+void avr_uart_send(const char c);
+
 #endif	/* __PPC_KERNEL_MPC10X_H */