powerpc/pseries: Move hvc_vio_init_early() prototype to shared location

Fixes the following W=1 kernel build warning(s):

 drivers/tty/hvc/hvc_vio.c:385:13: warning: no previous prototype for ‘hvc_vio_init_early’
 385 | void __init hvc_vio_init_early(void)
 | ^~~~~~~~~~~~~~~~~~
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210303124603.3150175-1-lee.jones@linaro.org

arch/powerpc/include/asm/hvconsole.h

@@ -24,5 +24,8 @@
 extern int hvc_get_chars(uint32_t vtermno, char *buf, int count);
 extern int hvc_put_chars(uint32_t vtermno, const char *buf, int count);
 
+/* Provided by HVC VIO */
+void hvc_vio_init_early(void);
+
 #endif /* __KERNEL__ */
 #endif /* _PPC64_HVCONSOLE_H */

arch/powerpc/platforms/pseries/pseries.h

@@ -43,9 +43,6 @@ extern void pSeries_final_fixup(void);
 /* Poweron flag used for enabling auto ups restart */
 extern unsigned long rtas_poweron_auto;
 
-/* Provided by HVC VIO */
-extern void hvc_vio_init_early(void);
-
 /* Dynamic logical Partitioning/Mobility */
 extern void dlpar_free_cc_nodes(struct device_node *);
 extern void dlpar_free_cc_property(struct property *);

arch/powerpc/platforms/pseries/setup.c

@@ -71,6 +71,7 @@
 #include <asm/swiotlb.h>
 #include <asm/svm.h>
 #include <asm/dtl.h>
+#include <asm/hvconsole.h>
 
 #include "pseries.h"
 #include "../../../../drivers/pci/pci.h"