x86/defconfigs: Remove useless UEVENT_HELPER_PATH

Remove the CONFIG_UEVENT_HELPER_PATH because:
1. It is disabled since commit

  1be01d4a57 ("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>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Adam Borowski <kilobyte@angband.pl>
Cc: "Ahmed S. Darwish" <darwish.07@gmail.com>
Cc: Alexey Brodkin <alexey.brodkin@synopsys.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: x86-ml <x86@kernel.org>
Link: https://lkml.kernel.org/r/1559635284-21696-1-git-send-email-krzk@kernel.org

arch/x86/configs/i386_defconfig

@@ -130,7 +130,6 @@ CONFIG_CFG80211=y
 CONFIG_MAC80211=y
 CONFIG_MAC80211_LEDS=y
 CONFIG_RFKILL=y
-CONFIG_UEVENT_HELPER_PATH="/sbin/hotplug"
 CONFIG_DEVTMPFS=y
 CONFIG_DEVTMPFS_MOUNT=y
 CONFIG_DEBUG_DEVRES=y

arch/x86/configs/x86_64_defconfig

@@ -129,7 +129,6 @@ CONFIG_CFG80211=y
 CONFIG_MAC80211=y
 CONFIG_MAC80211_LEDS=y
 CONFIG_RFKILL=y
-CONFIG_UEVENT_HELPER_PATH="/sbin/hotplug"
 CONFIG_DEVTMPFS=y
 CONFIG_DEVTMPFS_MOUNT=y
 CONFIG_DEBUG_DEVRES=y