zram: remove zram_sysfs file (v2)

Move zram sysfs code to zram drv and remove zram_sysfs.c
file. This gives ability to make static a number of previously
exported zram functions, used from zram sysfs, e.g. internal zram
zram_meta_alloc/free(). We also can drop zram_drv wrapper
functions, used from zram sysfs:
e.g. zram_reset_device()/__zram_reset_device() pair.

v2: as suggested by Greg K-H, move MODULE description to the
bottom of the file.

Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/zram/Makefile

@@ -1,3 +1,3 @@
-zram-y	:=	zram_drv.o zram_sysfs.o
+zram-y	:=	zram_drv.o
 
 obj-$(CONFIG_ZRAM)	+=	zram.o