move uartmem_getbaseaddr() to generic uart header

This moves uartmem_getbaseaddr() from an 8250-specific header to the
generic uart header. This is to accomodate non-8250 memory-mapped
UARTs.

Change-Id: Id25e7dab12b33bdd928f2aa4611d720aa79f3dee
Signed-off-by: David Hendricks <dhendrix@chromium.org>
Reviewed-on: http://review.coreboot.org/2422
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

src/include/uart.h

@@ -37,4 +37,8 @@ void uart_tx_flush(void);
 void uart_init(void);
 #endif
 
+#if CONFIG_HAVE_UART_MEMORY_MAPPED
+uint32_t uartmem_getbaseaddr(void);
+#endif
+
 #endif /* UART_H */