v7: introduce read_packet_u8() helper

Both before and after:
   text    data     bss     dec     hex filename
   4296       0       0    4296    10c8 apf_interpreter.arm.o
   text    data     bss     dec     hex filename
   5581       0       0    5581    15cd apf_interpreter.x86.o

Test: TreeHugger
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: I383e33eb174c45f8965395e4a0d251fd50305755
2 files changed