Use <linux/fscrypt.h> from Bionic

aosp/1184798 has updated the kernel headers to 5.4, so we no longer need
the file fscrypt_uapi.h.  In KeyUtil.cpp we also now don't need
<linux/fs.h>, but rather just the more specific <linux/fscrypt.h>.

Test: build
Bug: None
Change-Id: I56d17826eb7c3b95c74ce0435a4feae7f3cc325e
diff --git a/KeyUtil.cpp b/KeyUtil.cpp
index f822377..79a5102 100644
--- a/KeyUtil.cpp
+++ b/KeyUtil.cpp
@@ -21,7 +21,7 @@
 #include <string>
 
 #include <fcntl.h>
-#include <linux/fs.h>
+#include <linux/fscrypt.h>
 #include <openssl/sha.h>
 #include <sys/ioctl.h>
 
@@ -31,7 +31,6 @@
 
 #include "KeyStorage.h"
 #include "Utils.h"
-#include "fscrypt_uapi.h"
 
 namespace android {
 namespace vold {