generic: 5.15: copy config and patch from 5.10

Copy config and patches from kernel 5.10 to kernel 5.15

Signed-off-by: Ansuel Smith <ansuelsmth@gmail.com>

target/linux/generic/hack-5.15/910-kobject_uevent.patch

@@ -0,0 +1,32 @@
+From 0d37e6edc09c99e683dd91ca0e83bbc0df8477b3 Mon Sep 17 00:00:00 2001
+From: Felix Fietkau <nbd@nbd.name>
+Date: Sun, 16 Jul 2017 16:56:10 +0200
+Subject: lib: add uevent_next_seqnum()
+
+Signed-off-by: Felix Fietkau <nbd@nbd.name>
+---
+ include/linux/kobject.h |  5 +++++
+ lib/kobject_uevent.c    | 37 +++++++++++++++++++++++++++++++++++++
+ 2 files changed, 42 insertions(+)
+
+--- a/lib/kobject_uevent.c
++++ b/lib/kobject_uevent.c
+@@ -179,6 +179,18 @@ out:
+ 	return r;
+ }
+ 
++u64 uevent_next_seqnum(void)
++{
++	u64 seq;
++
++	mutex_lock(&uevent_sock_mutex);
++	seq = ++uevent_seqnum;
++	mutex_unlock(&uevent_sock_mutex);
++
++	return seq;
++}
++EXPORT_SYMBOL_GPL(uevent_next_seqnum);
++
+ /**
+  * kobject_synth_uevent - send synthetic uevent with arguments
+  *