riscv: vDSO: Remove --hash-style=both

When RISC-V borned, DT_GNU_HASH had already became the de-facto
standard so DT_HASH is just wasting storage space.  Remove the explicit
--hash-style=both setting and rely on the distro toolchain default,
which is most likely "gnu" (i.e. generating only DT_GNU_HASH, no
DT_HASH).

Following the logic of commit 48f6430
("arm64/vdso: Remove --hash-style=sysv").

Signed-off-by: Xi Ruoyao <xry111@xry111.site>
Link: https://lore.kernel.org/r/20250224112042.60282-2-xry111@xry111.site
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

Author: xry111

arch/riscv/kernel/vdso/Makefile

@@ -59,7 +59,7 @@ $(obj)/vdso.o: $(obj)/vdso.so
 $(obj)/vdso.so.dbg: $(obj)/vdso.lds $(obj-vdso) FORCE
 	$(call if_changed,vdsold_and_check)
 LDFLAGS_vdso.so.dbg = -shared -soname=linux-vdso.so.1 \
-	--build-id=sha1 --hash-style=both --eh-frame-hdr
+	--build-id=sha1 --eh-frame-hdr
 
 # strip rule for the .so file
 $(obj)/%.so: OBJCOPYFLAGS := -S