bpf: fix printing of memory operands in pseudoc asm dialect

The BPF backend was emitting memory operands in pseudo-C syntax
without surrounding parentheses.  These were being provided in the
corresponding instruction templates.

This was causing GCC emitting invalid instructions when finding inline
assembly with memory operands like:

	asm volatile (
	"r1 = *(u64 *)%[ctx_a];"
	"if r1 != 42 goto 1f;"
	"r1 = *(u64 *)%[ctx_b];"
	"if r1 != 42 goto 1f;"
	"r1 = *(u64 *)%[ctx_c];"
	"if r1 != 7 goto 1f;"
	"r1 /= 0;"
	"1:"
	:
	: [ctx_a]"m"(ctx.a),
	  [ctx_b]"m"(ctx.b),
	  [ctx_c]"m"(ctx.c)
	: "r1"
	);

This patch changes the backend to include the surrounding parentheses
in the printed representation of the memory operands (much like
surrounding brackets are included in normal asm syntax) and adapts the
impacted instruction templates accordingly.

Tested in target bpf-unknown-none, host x86_64-linux-gnu.

gcc/ChangeLog:

	* config/bpf/bpf.cc (bpf_print_operand_address): Include
	surrounding parenthesis around mem operands in pseudoc asm
	dialect.
	* config/bpf/bpf.md (*mov<MM:mode>): Adapt accordingly.
	(zero_extendhidi2): Likewise.
	(zero_extendqidi2): Likewise.
	(*extendsidi2): Likewise.
	(*extendsidi2): Likewise.
	(extendhidi2): Likewise.
	(extendqidi2): Likewise.
	(extendhisi2): Likewise.
	* config/bpf/atomic.md (atomic_add<AMO:mode>): Likewise.
	(atomic_and<AMO:mode>): Likewise.
	(atomic_or<AMO:mode>): Likewise.
	(atomic_xor<AMO:mode>): Likewise.
	(atomic_fetch_add<AMO:mode>): Likewise.
	(atomic_fetch_and<AMO:mode>): Likewise.
	(atomic_fetch_or<AMO:mode>): Likewise.
	(atomic_fetch_xor<AMO:mode>): Likewise.