sh: import missing private libraries from Linux 3.19

SuperH is supposed to support the Private Library feature, but it is
actually not working.

If CONFIG_USE_PRIVATE_LIBGCC is enabled, the build fails for the
undefined references to '__sdivsi3_i4i' and '__udivsi3_i4i'.

To fix this error, import missing libraries from Linux 3.19
and adjust them for U-Boot:
  - Remove "#include <linux/module.h>" and "EXPORT_SYMBOL(...)"
  - Use SPDX-License-Identifier
  - Remove white space

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Signed-off-by: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>
diff --git a/arch/sh/lib/ashrdi3.c b/arch/sh/lib/ashrdi3.c
new file mode 100644
index 0000000..f30359b
--- /dev/null
+++ b/arch/sh/lib/ashrdi3.c
@@ -0,0 +1,27 @@
+#include "libgcc.h"
+
+long long __ashrdi3(long long u, word_type b)
+{
+	DWunion uu, w;
+	word_type bm;
+
+	if (b == 0)
+		return u;
+
+	uu.ll = u;
+	bm = 32 - b;
+
+	if (bm <= 0) {
+		/* w.s.high = 1..1 or 0..0 */
+		w.s.high =
+		    uu.s.high >> 31;
+		w.s.low = uu.s.high >> -bm;
+	} else {
+		const unsigned int carries = (unsigned int) uu.s.high << bm;
+
+		w.s.high = uu.s.high >> b;
+		w.s.low = ((unsigned int) uu.s.low >> b) | carries;
+	}
+
+	return w.ll;
+}