mesh: Use u8_t instead of bitfields for 8-bit wide values
mesh: Use u8_t instead of bitfields for 8-bit wide values

It's cleaner to use single u8_t variables for values which require
exactly 8 bits.

X-Original-Commit: 7d857e99eb46708663dcb346c343638114de46c7

apache/mynewt-nimble,apache/mynewt-nimble,apache/mynewt-nimble,apache/mynewt-nimble,apache/mynewt-nimble