um: configs: Remove useless UEVENT_HELPER_PATH

Remove the CONFIG_UEVENT_HELPER_PATH because:
1. It is disabled since commit 1be01d4a ("driver: base: Disable
   CONFIG_UEVENT_HELPER by default") as its dependency (UEVENT_HELPER) was
   made default to 'n',
2. It is not recommended (help message: "This should not be used today
   [...] creates a high system load") and was kept only for ancient
   userland,
3. Certain userland specifically requests it to be disabled (systemd
   README: "Legacy hotplug slows down the system and confuses udev").
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Acked-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Richard Weinberger <richard@nod.at>

arch/um/configs/i386_defconfig

@@ -36,7 +36,6 @@ CONFIG_XTERM_CHAN=y
 CONFIG_CON_CHAN="pts"
 CONFIG_SSL_CHAN="pts"
 CONFIG_UML_SOUND=m
-CONFIG_UEVENT_HELPER_PATH="/sbin/hotplug"
 CONFIG_DEVTMPFS=y
 CONFIG_DEVTMPFS_MOUNT=y
 CONFIG_BLK_DEV_UBD=y

arch/um/configs/x86_64_defconfig

@@ -34,7 +34,6 @@ CONFIG_XTERM_CHAN=y
 CONFIG_CON_CHAN="pts"
 CONFIG_SSL_CHAN="pts"
 CONFIG_UML_SOUND=m
-CONFIG_UEVENT_HELPER_PATH="/sbin/hotplug"
 CONFIG_DEVTMPFS=y
 CONFIG_DEVTMPFS_MOUNT=y
 CONFIG_BLK_DEV_UBD=y