MIPS: Malta: Improve system memory detection for '{e, }memsize' >= 2G

Using kstrtol to parse the "{e,}memsize" variables was wrong because this
parses signed long numbers. In case of '{e,}memsize' >= 2G, the top bit
is set, resulting to -ERANGE errors and possibly random system memory
boundaries. We fix this by replacing "kstrtol" with "kstrtoul".
We also improve the code to check the kstrtoul return value and
print a warning if an error was returned.
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Cc: <stable@vger.kernel.org> # v3.15+
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/7543/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/mti-malta/malta-memory.c

@@ -35,13 +35,19 @@ fw_memblock_t * __init fw_getmdesc(int eva)
 	/* otherwise look in the environment */
 
 	memsize_str = fw_getenv("memsize");
-	if (memsize_str)
-		tmp = kstrtol(memsize_str, 0, &memsize);
+	if (memsize_str) {
+		tmp = kstrtoul(memsize_str, 0, &memsize);
+		if (tmp)
+			pr_warn("Failed to read the 'memsize' env variable.\n");
+	}
 	if (eva) {
 	/* Look for ememsize for EVA */
 		ememsize_str = fw_getenv("ememsize");
-		if (ememsize_str)
-			tmp = kstrtol(ememsize_str, 0, &ememsize);
+		if (ememsize_str) {
+			tmp = kstrtoul(ememsize_str, 0, &ememsize);
+			if (tmp)
+				pr_warn("Failed to read the 'ememsize' env variable.\n");
+		}
 	}
 	if (!memsize && !ememsize) {
 		pr_warn("memsize not set in YAMON, set to default (32Mb)\n");