powerpc/epapr: export epapr_hypercall_start

This fixes breakage introduced by the following commit:

  commit 6d2d82627f4f1e96a33664ace494fa363e0495cb
  Author: Liu Yu-B13201 <Yu.Liu@freescale.com>
  Date:   Tue Jul 3 05:48:56 2012 +0000

    PPC: Don't use hardcoded opcode for ePAPR hcall invocation

when a driver that uses ePAPR hypercalls is built as a module.
Reported-by: NGeert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: NScott Wood <scottwood@freescale.com>
Signed-off-by: NAlexander Graf <agraf@suse.de>

arch/powerpc/kernel/ppc_ksyms.c

@@ -43,6 +43,7 @@
 #include <asm/dcr.h>
 #include <asm/ftrace.h>
 #include <asm/switch_to.h>
+#include <asm/epapr_hcalls.h>
 
 #ifdef CONFIG_PPC32
 extern void transfer_to_handler(void);
@@ -192,3 +193,7 @@ EXPORT_SYMBOL(__arch_hweight64);
 #ifdef CONFIG_PPC_BOOK3S_64
 EXPORT_SYMBOL_GPL(mmu_psize_defs);
 #endif
+
+#ifdef CONFIG_EPAPR_PARAVIRT
+EXPORT_SYMBOL(epapr_hypercall_start);
+#endif