parisc: Fix ftrace function tracer

Fix the FTRACE function tracer for 32- and 64-bit kernel.
The former code was horribly broken.

Reimplement most coding in assembly and utilize optimizations, e.g. put
mcount() and ftrace_stub() into one L1 cacheline.

Signed-off-by: Helge Deller <deller@gmx.de>
diff --git a/arch/parisc/Kconfig.debug b/arch/parisc/Kconfig.debug
index bc989e5..68b7cbd 100644
--- a/arch/parisc/Kconfig.debug
+++ b/arch/parisc/Kconfig.debug
@@ -2,9 +2,13 @@
 
 source "lib/Kconfig.debug"
 
+config TRACE_IRQFLAGS_SUPPORT
+	def_bool y
+
 config DEBUG_RODATA
        bool "Write protect kernel read-only data structures"
        depends on DEBUG_KERNEL
+       default y
        help
          Mark the kernel read-only data as write-protected in the pagetables,
          in order to catch accidental (and incorrect) writes to such const