Blackfin arch: use do_div() for the 64bit division as pointed out by Bernd

If you need a 64 bit divide in the kernel, use asm/div64.h.
Revert the addition of udivdi3.

Cc: Bernd Schmidt <bernd.schmidt@analog.com>
Signed-off-by: Mike Frysinger <michael.frysinger@analog.com>
Signed-off-by: Bryan Wu <bryan.wu@analog.com>

diff --git a/arch/blackfin/kernel/setup.c b/arch/blackfin/kernel/setup.c
index dfe06b0..eee5a1f 100644
--- a/arch/blackfin/kernel/setup.c
+++ b/arch/blackfin/kernel/setup.c
@@ -43,6 +43,7 @@
 #include <asm/cacheflush.h>
 #include <asm/blackfin.h>
 #include <asm/cplbinit.h>
+#include <asm/div64.h>
 #include <asm/fixed_code.h>
 #include <asm/early_printk.h>
 
@@ -504,13 +505,17 @@
 
 unsigned long sclk_to_usecs(unsigned long sclk)
 {
-	return (USEC_PER_SEC * (u64)sclk) / get_sclk();
+	u64 tmp = USEC_PER_SEC * (u64)sclk;
+	do_div(tmp, get_sclk());
+	return tmp;
 }
 EXPORT_SYMBOL(sclk_to_usecs);
 
 unsigned long usecs_to_sclk(unsigned long usecs)
 {
-	return (get_sclk() * (u64)usecs) / USEC_PER_SEC;
+	u64 tmp = get_sclk() * (u64)usecs;
+	do_div(tmp, USEC_PER_SEC);
+	return tmp;
 }
 EXPORT_SYMBOL(usecs_to_sclk);