powerpc/optprobes: Remove unused routine patch_imm32_load_insns()

powerpc/optprobes: Remove unused routine patch_imm32_load_insns()

Commit 650b55b707fd ("powerpc: Add prefixed instructions to instruction
data type") removed the use of patch_imm32_load_insns(). Clean it up
to fix this W=1 compile error :

../arch/powerpc/kernel/optprobes.c:149:6: error: no previous prototype for ‘patch_imm32_load_insns’ [-Werror=missing-prototypes]
  149 | void patch_imm32_load_insns(unsigned int val, kprobe_opcode_t *addr)

Fixes: 650b55b707fd ("powerpc: Add prefixed instructions to instruction data type")
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210104143206.695198-11-clg@kaod.org