perf: mkdir ${B} -> mkdir -p ${B}

${B} is the default cwd of tasks, so there might be race issues such as:
| mkdir: cannot create directory `/path/to/work/qemux86-poky-linux/perf/1.0-r9/perf-1.0/': File exists
[snip]
NOTE: recipe perf-1.0-r9: task do_configure: Failed

(From OE-Core rev: eb3d1dac724144637a86e8124b7b6b91bbeab822)

Signed-off-by: Robert Yang <liezhi.yang@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-kernel/perf/perf.bb

@@ -118,7 +118,7 @@ do_install() {
 do_configure_prepend () {
     # Fix for rebuilding
     rm -rf ${B}/
-    mkdir ${B}/
+    mkdir -p ${B}/
 
     #kernels before 3.1 do not support WERROR env variable
     sed -i 's,-Werror ,,' ${S}/tools/perf/Makefile