erofs: remove a void EROFS_VERSION macro set in Makefile

Since commit 4f761fa2 ("erofs: rename errln/infoln/debugln to
erofs_{err, info, dbg}") the defined macro EROFS_VERSION has no affect,
therefore removing it from the Makefile is a non-functional change.

Link: https://lore.kernel.org/r/20201030122839.25431-1-vladimir@tuxera.comReviewed-by: NGao Xiang <hsiangkao@redhat.com>
Reviewed-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NVladimir Zapolskiy <vladimir@tuxera.com>
Signed-off-by: NGao Xiang <hsiangkao@redhat.com>

fs/erofs/Makefile

 # SPDX-License-Identifier: GPL-2.0-only
 
-EROFS_VERSION = "1.0"
-
-ccflags-y += -DEROFS_VERSION=\"$(EROFS_VERSION)\"
-
 obj-$(CONFIG_EROFS_FS) += erofs.o
 erofs-objs := super.o inode.o data.o namei.o dir.o utils.o
 erofs-$(CONFIG_EROFS_FS_XATTR) += xattr.o
 erofs-$(CONFIG_EROFS_FS_ZIP) += decompressor.o zmap.o zdata.o
-