ARM: mstar: remove unused config MACH_MERCURY

Commit 312b62b6610c ("ARM: mstar: Add machine for MStar/Sigmastar Armv7
SoCs") adds the config MACH_INFINITY and MACH_MERCURY. The MACH_INFINITY
config is used in the gpio-msc313 driver, but the MACH_MERCURY config is
never used to configure anything in the kernel tree.

Remove the unused config MACH_MERCURY.

Signed-off-by: Lukas Bulwahn <[e-mail]>
Acked-by: Romain Perier <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Arnd Bergmann <[e-mail]>

arch/arm/mach-mstar/Kconfig

···
 	help
 	  Support for MStar/Sigmastar infinity IP camera SoCs.
 
-config MACH_MERCURY
-	bool "MStar/Sigmastar mercury SoC support"
-	default ARCH_MSTARV7
-	help
-	  Support for MStar/Sigmastar mercury dash camera SoCs.
-	  Note that older Mercury2 SoCs are ARM9 based and not supported.
-
 endif