riscv: Unconditionally use linker relaxation

Now that the minimum supported version of LLVM for building the kernel
has been bumped to 15.0.0, CONFIG_RISCV_USE_LINKER_RELAXATION will
always be enabled, so it can be removed.

Acked-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Link: https://lore.kernel.org/r/20250821-bump-min-llvm-ver-15-v2-8-635f3294e5f0@kernel.org
Signed-off-by: Nathan Chancellor <nathan@kernel.org>

Author: nathanchance

arch/riscv/Kconfig

@@ -246,15 +246,9 @@ config HAVE_SHADOW_CALL_STACK
 	# https://github.com/riscv-non-isa/riscv-elf-psabi-doc/commit/a484e843e6eeb51f0cb7b8819e50da6d2444d769
 	depends on $(ld-option,--no-relax-gp)
 
-config RISCV_USE_LINKER_RELAXATION
-	def_bool y
-	# https://github.com/llvm/llvm-project/commit/6611d58f5bbcbec77262d392e2923e1d680f6985
-	depends on !LD_IS_LLD || LLD_VERSION >= 150000
-
 # https://github.com/llvm/llvm-project/commit/bbc0f99f3bc96f1db16f649fc21dd18e5b0918f6
 config ARCH_HAS_BROKEN_DWARF5
 	def_bool y
-	depends on RISCV_USE_LINKER_RELAXATION
 	# https://github.com/llvm/llvm-project/commit/1df5ea29b43690b6622db2cad7b745607ca4de6a
 	depends on AS_IS_LLVM && AS_VERSION < 180000
 	# https://github.com/llvm/llvm-project/commit/7ffabb61a5569444b5ac9322e22e5471cc5e4a77

arch/riscv/Makefile

@@ -46,17 +46,10 @@ else
 	KBUILD_LDFLAGS += -melf32lriscv
 endif
 
-ifndef CONFIG_RISCV_USE_LINKER_RELAXATION
-	KBUILD_CFLAGS += -mno-relax
-	KBUILD_AFLAGS += -mno-relax
-ifndef CONFIG_AS_IS_LLVM
-	KBUILD_CFLAGS += -Wa,-mno-relax
-	KBUILD_AFLAGS += -Wa,-mno-relax
-endif
 # LLVM has an issue with target-features and LTO: https://github.com/llvm/llvm-project/issues/59350
 # Ensure it is aware of linker relaxation with LTO, otherwise relocations may
 # be incorrect: https://github.com/llvm/llvm-project/issues/65090
-else ifeq ($(CONFIG_LTO_CLANG),y)
+ifeq ($(CONFIG_LTO_CLANG),y)
 	KBUILD_LDFLAGS += -mllvm -mattr=+c -mllvm -mattr=+relax
 endif