gemini: stop overriding CONFIG_EXPERT

The fragment carries "# CONFIG_EXPERT is not set" while every other
target inherits CONFIG_EXPERT=y from target/linux/generic. That looks
like an artefact of an imported defconfig, and it has a consequence: a
symbol whose prompt is conditional on EXPERT stops being settable with
EXPERT off and silently takes its own default, so the generic fragment
cannot control it.

CONFIG_VT is one of those, declared bool "Virtual terminal" if EXPERT
with default y, which is why the "# CONFIG_VT is not set" in generic has
no effect on this target today. Drop the override so gemini resolves such
symbols the same way as everything else.

Signed-off-by: Daniel Golle <daniel@makrotopia.org>

target/linux/gemini/config-6.18

@@ -148,7 +148,6 @@ CONFIG_EDAC_SUPPORT=y
 CONFIG_EEPROM_93CX6=y
 CONFIG_ELF_CORE=y
 CONFIG_EXCLUSIVE_SYSTEM_RAM=y
-# CONFIG_EXPERT is not set
 CONFIG_EXT4_FS=y
 CONFIG_EXTCON=y
 CONFIG_FARADAY_FTINTC010=y