rk3399: Add CFI debug information to SRAM functions

rk3399: Add CFI debug information to SRAM functions

Commit b91d935feebdf2c3edef19949023645b6cb34b20
("Add CFI debug frame information for ASM functions") modifies the
assembly macros 'func' and 'endfunc' to include CFI debug frame
information.

The rockchip platform uses a custom version of the 'func' macro with the
common 'endfunc' macro. The custom macro wasn't updated in
b91d935feebdf2c3edef19949023645b6cb34b20 resulting in the following
build error:
  plat/rockchip/rk3399/drivers/pmu/plat_pmu_macros.S: Assembler messages:
  plat/rockchip/rk3399/drivers/pmu/plat_pmu_macros.S:155: Error: .cfi_endproc without corresponding .cfi_startproc
  Makefile:532: recipe for target 'build/rk3399/release/bl31/plat_helpers.o' failed
  make: *** [build/rk3399/release/bl31/plat_helpers.o] Error 1

Fixing this by updating the sram_func macro in the rk3399 port.

Fixes: b91d935feebdf2c3edef19949023645b6cb34b20 ("Add CFI debug frame information for ASM functions")
Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>