riscv: fix RISCV_ISA_SVPBMT kconfig dependency warning

RISCV_ISA_SVPBMT selects RISCV_ALTERNATIVE which depends on !XIP_KERNEL.
Therefore RISCV_ISA_SVPBMT should also depend on !XIP_KERNEL so
quieten this kconfig warning:

WARNING: unmet direct dependencies detected for RISCV_ALTERNATIVE
  Depends on [n]: !XIP_KERNEL [=y]
  Selected by [y]:
  - RISCV_ISA_SVPBMT [=y] && 64BIT [=y] && MMU [=y]

Fixes: ff689fd ("riscv: add RISC-V Svpbmt extension support")
Signed-off-by: Randy Dunlap <[email protected]>
Cc: [email protected]
Reviewed-by: Heiko Stuebner <[email protected]>
Link: https://lore.kernel.org/r/[email protected]/
Signed-off-by: Palmer Dabbelt <[email protected]>

Author: rddunlap

arch/riscv/Kconfig

@@ -386,6 +386,7 @@ config RISCV_ISA_C
 config RISCV_ISA_SVPBMT
 	bool "SVPBMT extension support"
 	depends on 64BIT && MMU
+	depends on !XIP_KERNEL
 	select RISCV_ALTERNATIVE
 	default y
 	help