m68k: sun3: Fix DEBUG_MMU_EMU build

With DEBUG_MMU_EMU enabled:

arch/m68k/sun3/mmu_emu.c: In function ‘mmu_emu_handle_fault’:
arch/m68k/sun3/mmu_emu.c:420:38: error: implicit declaration of function ‘get_fs’; did you mean ‘sget_fc’? [-Werror=implicit-function-declaration]
420 | pr_info("seg:%ld crp:%p ->", get_fs().seg, crp);
| ^~~~~~

[...]

arch/m68k/sun3/mmu_emu.c:420:46: error: request for member ‘seg’ in something not a structure or union
420 | pr_info("seg:%ld crp:%p ->", get_fs().seg, crp);
| ^

Fix this by reintroducing and using a helper to retrieve the current
value of the DFC register.

While at it, replace "%p" by "%px", as there is no point in printing
obfuscated pointers during debugging.

Fixes: 9fde0348640252c7 ("m68k: Remove set_fs()")
Signed-off-by: Geert Uytterhoeven <[e-mail]>
Link: https://lore.kernel.org/[e-mail]

arch/m68k/include/asm/processor.h

···
 			      "movec %0,%/dfc\n\t"
 			      : /* no outputs */ : "r" (val) : "memory");
 }
+
+static inline unsigned long get_fc(void)
+{
+	unsigned long val;
+
+	__asm__ ("movec %/dfc,%0" : "=r" (val) : );
+
+	return val;
+}
 #else
 static inline void set_fc(unsigned long val)
 {
+}
+
+static inline unsigned long get_fc(void)
+{
+	return USER_DATA;
 }
 #endif /* CONFIG_CPU_HAS_ADDRESS_SPACES */
 

arch/m68k/sun3/mmu_emu.c

···
 	}
 
 #ifdef DEBUG_MMU_EMU
-	pr_info("%s: vaddr=%lx type=%s crp=%p\n", __func__, vaddr,
+	pr_info("%s: vaddr=%lx type=%s crp=%px\n", __func__, vaddr,
 		str_read_write(read_flag), crp);
 #endif
 
···
 		pte_val (*pte) |= SUN3_PAGE_ACCESSED;
 
 #ifdef DEBUG_MMU_EMU
-	pr_info("seg:%ld crp:%p ->", get_fs().seg, crp);
+	pr_info("seg:%ld crp:%px ->", get_fc(), crp);
 	print_pte_vaddr (vaddr);
 	pr_cont("\n");
 #endif