[REPORT] RESERVE_BRK() doesn't work for some cases

[Byungchul Park]

commit a1e2c031ec3 "x86/mm: Simplify RESERVE_BRK()" changed the behavior
by compiler and assembler.

Some strings obtained just by __stringify() cannot be interpreted by
some assemblers.

It might need to allow to put input for size within inline asm.

	Byungchul