FRV: Make NOMMU-mode work with base addresses other than 0xC0000000 [try #2]

Make NOMMU-mode work with base addresses other than 0xC0000000 by:

(1) Giving the code that sets up the protection registers the right address
in __sdram_base. Rather than being hard coded to 0xC0000000, the value
of __page_offset is obtained from the linker script.

(2) Eliminate the check in __switch_to() that verifies the current thread
info is in the 0xCxxxxxxx region.

Signed-off-by: David Howells <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

arch/frv/kernel/head.inc

···
 #ifdef CONFIG_MMU
 __sdram_base = 0x00000000		/* base address to which SDRAM relocated */
 #else
-__sdram_base = 0xc0000000		/* base address to which SDRAM relocated */
+__sdram_base = __page_offset		/* base address to which SDRAM relocated */
 #endif

arch/frv/kernel/switch_to.S

···
 	movgs		gr14,lr
 	bar
 
-	srli		gr15,#28,gr5
-	subicc		gr5,#0xc,gr0,icc0
-	beq		icc0,#0,111f
-	break
-	nop
-111:
-
 	# jump to __switch_back or ret_from_fork as appropriate
 	# - move prev to GR8
 	movgs		gr4,psr