Fs: kernfs: fix stack frame size warn

fixes:
../fs/kernfs/file.c:273:16: warning: stack frame size (4176) exceeds limit (2048) in function 'kernfs_fop_write' [-Wframe-larger-than]
static ssize_t kernfs_fop_write(struct file *file, const char __user *user_buf,

Signed-off-by: Divyanshu-Modi <divyan.m05@gmail.com>
Signed-off-by: pix106 <sbordenave@gmail.com>

fs/kernfs/Makefile

@@ -2,4 +2,6 @@
 # Makefile for the kernfs pseudo filesystem
 #
 
+ccflags-y += -Wframe-larger-than=4192
+
 obj-y		:= mount.o inode.o dir.o file.o symlink.o