MIPS: allow building with kcov coverage

Add ARCH_HAS_KCOV and HAVE_GCC_PLUGINS to MIPS config.
Disable instrumentation of vdso to avoid build failure.

Signed-off-by: Alexey Khoroshilov <[e-mail]>
Signed-off-by: Paul Burton <[e-mail]>
Cc: Ralf Baechle <[e-mail]>
Cc: James Hogan <[e-mail]>
Cc: [e-mail]
Cc: [e-mail]

arch/mips/Kconfig

···
 	select SYSCTL_EXCEPTION_TRACE
 	select VIRT_TO_BUS
 	select ARCH_HAS_PTE_SPECIAL if !(32BIT && CPU_HAS_RIXI)
+	select ARCH_HAS_KCOV
+	select HAVE_GCC_PLUGINS
 
 menu "Machine selection"
 

arch/mips/vdso/Makefile

···
 
 GCOV_PROFILE := n
 UBSAN_SANITIZE := n
+KCOV_INSTRUMENT := n
 
 #
 # Shared build commands.