[RISCV] Fix comment in compress-opt-branch.ll to match description. NFC

Test description says constant does not fit in 12 bits, but the constant
used was -2048 which does fit in 12 bits. Update to -2049.

Also remove uses of -NOT in favor of positive checks. One of the -NOT
should have been using RESBROPT instead of "c.beqz" so that it would
check for the absense of the correct instruction based on the sed
replacement on the RUN line.

Author: topperc

llvm/test/CodeGen/RISCV/compress-opt-branch.ll

@@ -270,9 +270,14 @@ if.end:
 
 ; constant is big and do not fit in 12 bit (imm), fit in i32
 ; RV32IFDC-LABEL: <f_big_ledge_pos>:
-; RV32IFDC-NOT: RESBROPT
+; RV32IFDC: c.li [[REG:.*]], 0x1
+; RV32IFDC: c.slli [[REG]], 0xb
+; RV32IFDC: RESBRNORMAL [[ANOTHER:.*]], [[REG]], [[PLACE:.*]]
 ; --- no compress extension
-; nothing to check.
+; RV32IFD-LABEL: <f_big_ledge_pos>:
+; RV32IFD: addi [[REG1:.*]], zero, 0x1
+; RV32IFD: slli [[REG2:.*]], [[REG1]], 0xb
+; RV32IFD: RESBRNORMAL [[ANOTHER:.*]], [[REG2]], [[PLACE:.*]]
 define i32 @f_big_ledge_pos(i32 %in0) minsize {
   %cmp = icmp CMPCOND i32 %in0, 2048
   br i1 %cmp, label %if.then, label %if.else
@@ -290,11 +295,16 @@ if.end:
 
 ; constant is big and do not fit in 12 bit (imm), fit in i32
 ; RV32IFDC-LABEL: <f_big_ledge_neg>:
-; RV32IFDC-NOT: c.beqz
+; RV32IFDC: c.lui [[REG1:.*]], 0xfffff
+; RV32IFDC: addi [[REG2:.*]], [[REG1]], 0x7ff
+; RV32IFDC: RESBRNORMAL [[ANOTHER:.*]], [[REG]], [[PLACE:.*]]
 ; --- no compress extension
-; nothing to check.
+; RV32IFD-LABEL: <f_big_ledge_neg>:
+; RV32IFD: lui [[REG1:.*]], 0xfffff
+; RV32IFD: addi [[REG2:.*]], [[REG1]], 0x7ff
+; RV32IFD: RESBRNORMAL [[ANOTHER:.*]], [[REG2]], [[PLACE:.*]]
 define i32 @f_big_ledge_neg(i32 %in0) minsize {
-  %cmp = icmp CMPCOND i32 %in0, -2048
+  %cmp = icmp CMPCOND i32 %in0, -2049
   br i1 %cmp, label %if.then, label %if.else
 if.then:
   %call = shl i32 %in0, 1