arch/riscv: Print the page table structure after construction

A new Kconfig option, DEBUG_PRINT_PAGE_TABLES, is added to control this
behaviour. It is currently only available on RISC-V, but other
architectures can use it, too, should the need arise.

Change-Id: I52a863d8bc814ab3ed3a1f141d0a77edc6e4044d
Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net>
Reviewed-on: https://review.coreboot.org/16015
Tested-by: build bot (Jenkins)
Reviewed-by: Martin Roth <martinroth@google.com>

src/Kconfig

@@ -1127,6 +1127,14 @@ config DEBUG_BOOT_STATE
 	  Control debugging of the boot state machine.  When selected displays
 	  the state boundaries in ramstage.
 
+config DEBUG_PRINT_PAGE_TABLES
+	bool "Print the page tables after construction"
+	default n
+	depends on ARCH_RISCV
+	help
+	  After the page tables have been built, print them on the debug
+	  console.
+
 endmenu
 
 # These probably belong somewhere else, but they are needed somewhere.