microblaze: Remove noMMU code

This configuration is obsolete and likely none is really using it. That's
why remove it to simplify code.

Note about CONFIG_MMU in hw_exception_handler.S is left intentionally
for better comment understanding.

Cc: Mike Rapoport <rppt@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/43486cab370e0c0a79860120b71e0caac75a7e44.1606397528.git.michal.simek@xilinx.com

arch/microblaze/kernel/head.S

@@ -34,7 +34,6 @@
 #include <asm/page.h>
 #include <linux/of_fdt.h>		/* for OF_DT_HEADER */
 
-#ifdef CONFIG_MMU
 #include <asm/setup.h> /* COMMAND_LINE_SIZE */
 #include <asm/mmu.h>
 #include <asm/processor.h>
@@ -48,8 +47,6 @@ empty_zero_page:
 swapper_pg_dir:
 	.space	PAGE_SIZE
 
-#endif /* CONFIG_MMU */
-
 .section .rodata
 .align 4
 endian_check:
@@ -108,8 +105,6 @@ _copy_fdt:
 	addik	r3, r3, -4 /* descrement loop */
 no_fdt_arg:
 
-#ifdef CONFIG_MMU
-
 #ifndef CONFIG_CMDLINE_BOOL
 /*
  * handling command line
@@ -329,7 +324,6 @@ turn_on_mmu:
 	nop
 
 start_here:
-#endif /* CONFIG_MMU */
 
 	/* Initialize small data anchors */
 	addik	r13, r0, _KERNEL_SDA_BASE_
@@ -345,11 +339,6 @@ start_here:
 	brald	r15, r11
 	nop
 
-#ifndef CONFIG_MMU
-	addik	r15, r0, machine_halt
-	braid	start_kernel
-	nop
-#else
 	/*
 	 * Initialize the MMU.
 	 */
@@ -383,4 +372,3 @@ kernel_load_context:
 	nop
 	rted	r17, 0		/* enable MMU and jump to start_kernel */
 	nop
-#endif /* CONFIG_MMU */