PPC: Move asm helpers to U-Boot arch Jamfile

* the OpenFirmware arch/ppc/Jamfile already has it, so move it to avoid duplicated symbols.

src/system/boot/arch/ppc/Jamfile

@@ -19,14 +19,13 @@ KernelMergeObject boot_arch_$(TARGET_ARCH).o :
 	debug_uart_8250.cpp
 	arch_uart_8250.cpp
 	arch_elf.cpp
-	arch_cpu_asm.S
 	: # additional flags
 	:
 	$(kernelArchObjects)
 	$(kernelLibArchObjects)
 ;
 
-SEARCH on [ FGristFiles arch_elf.cpp arch_uart_8250.cpp arch_cpu_asm.S ]
+SEARCH on [ FGristFiles arch_elf.cpp arch_uart_8250.cpp ]
     = [ FDirName $(HAIKU_TOP) src system kernel arch $(TARGET_ARCH) ] ;
 
 SEARCH on [ FGristFiles debug_uart_8250.cpp ]

src/system/boot/platform/u-boot/arch/ppc/Jamfile

@@ -13,7 +13,7 @@ KernelMergeObject boot_platform_u-boot_ppc.o :
 	shell.S
 
 	#arch_mmu.cpp
-	#arch_cpu_asm.S
+	arch_cpu_asm.S
 	arch_start_kernel.S
 	arch_cpu.cpp
 	#mmu.cpp