linux: Get rid of 000-keep_initrafs_the_default.patch

linux: Get rid of 000-keep_initrafs_the_default.patch

With that patch in place for initramfs no additional options are
reported for "/" partition. What's really important is missing
info about sizes. Which in its turn makes opkg think that there's
no space on "/" partition to install software.

I understand that's a sort of corner-case, people rarely install
packages on ramfs but anyways why not?

Just in case that's what I see with the patch:
---------------------->8--------------------
root@lede:/# cat /proc/mounts
rootfs / rootfs rw 0 0
proc /proc proc rw,nosuid,nodev,noexec,noatime 0 0
sysfs /sys sysfs rw,nosuid,nodev,noexec,noatime 0 0
tmpfs /tmp tmpfs rw,nosuid,nodev,noatime 0 0
tmpfs /dev tmpfs rw,nosuid,relatime,size=512k,mode=755 0 0
devpts /dev/pts devpts rw,nosuid,noexec,relatime,mode=600 0 0
debugfs /sys/kernel/debug debugfs rw,noatime 0 0
---------------------->8--------------------

And without:
---------------------->8--------------------
root@lede:/# cat /proc/mounts
rootfs / rootfs rw,size=256168k,nr_inodes=32021 0 0
proc /proc proc rw,nosuid,nodev,noexec,noatime 0 0
sysfs /sys sysfs rw,nosuid,nodev,noexec,noatime 0 0
tmpfs /tmp tmpfs rw,nosuid,nodev,noatime 0 0
tmpfs /dev tmpfs rw,nosuid,relatime,size=512k,mode=755 0 0
devpts /dev/pts devpts rw,nosuid,noexec,relatime,mode=600 0 0
debugfs /sys/kernel/debug debugfs rw,noatime 0 0
---------------------->8--------------------

Note how different is entry for rootfs.

And given there's no known rationale for that patch we're
getting rid of it.

Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Cc: Jonas Gorski <jonas.gorski@gmail.com>
Cc: Rafał Miłecki <zajec5@gmail.com>
Cc: John Crispin <john@phrozen.org>
Cc: Felix Fietkau <nbd@nbd.name>